Sourdough American Flag Cake

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My sourdough American flag cake is made with from-scratch sourdough lemon sheet cake, homemade whipped cream frosting, and decorated with fresh berries. It’s moist, light, and refreshing, making it the perfect 4th of July cake or summer dessert!

This year for the 4th of July, I wanted to do something extra special. Last year I created my American flag taco dip, so this year I wanted to do something sweet. After all, it’s the 250th anniversary of the USA!

The light lemon taste mixed with the moist sourdough cake makes the most refreshing baked good for summer. If you’re looking for something that’s light and fresh, you’re going to love this flag cake recipe!

Why You’ll Love This Recipe

1. Simple and easy flag cake design: decorating this cake is so simple, even little kids can help!
2. Not too heavy or too sweet: the lemon cake is so light and fluffy, and the whipped cream frosting is like a cloud, both perfectly sweetened.
3. Perfect for the 4th of July: you can get 12 slices out of this cake, making it great for a 4th of July party or sharing with friends and neighbors.
4. No need to bring cake ingredients to room temperature: unlike most cake recipes, you don’t have to bring the eggs and dairy products to room temperature before baking.

Ingredients

For the Sourdough Lemon Cake

• avocado oil: this is my favorite wholesome oil to make cakes, you can swap it for coconut oil but not olive oil
• raw cane sugar: this is a good wholesome swap for regular table sugar
• eggs: large eggs work well for this recipe
• pure vanilla extract: I don’t recommend imitation vanilla
• sourdough discard: you can also use fed starter if desired
• milk: I use whole dairy milk but you can use any, just make sure it’s unsweetened 
• sour cream: this makes a moist cake, you can also use plain unsweetened yogurt
• sea salt: I recommend sticking to sea salt, it’s a good wholesome option
• lemon zest: the best way to zest a lemon is with a microplane
• lemon juice: fresh lemon juice works best but pure bottled works too
• baking powder: I always recommend an aluminum-free brand like Rumford
• baking soda: any will work
• all-purpose flour: I use and recommend unbleached organic all-prupose flour

For the Whipped Cream Frosting

• heavy whipping cream: organic is best to eliminate additives
• pure vanilla extract: I don’t recommend imitation vanilla
• raw cane sugar: this is a good wholesome swap for regular table sugar
• plain cream cheese: I recommend a brand with little to no additives

What You Need for the Flag Design

• blueberries: I recommend organic or home-grown/locally-grown but regular works
• raspberries: I recommend organic or home-grown/locally-grown but regular works

Tools You May Need

• medium sized sheet pan (approximately 12″ x 9″)
• mixing bowl
• electric hand mixer
• cooling rack

How to Make Sourdough American Flag Cake

Preheat oven to 350 degrees Fahrenheit, get cream cheese out of fridge so it can warm for the frosting, and butter/flour a medium stainless steel rimmed sheet pan (approximately 12”x 9”). Set aside.

Make the Sourdough Lemon Sheet Cake

In a large mixing bowl add avocado oil and sugar. Mix with an electric mixer on low speed for 2 minutes.

Add eggs one at a time. Mix each into the mixture on low speed until completely combined both times.

Add in vanilla, sourdough discard, milk, sour cream, salt, lemon zest, lemon juice, baking powder, and baking soda (wait to add baking powder and baking soda if you’re doing the optional cold ferment step below). Mix on low-medium speed until everything is combined and no clumps are left, about 30 seconds.

Add in flour and mix on medium speed JUST UNTIL combined. Do not over mix.

Optional – At this point you can either continue the recipe or place the batter in the fridge, covered, for 12-24 hours to ferment for more sourdough fermentation benefits. When you’re ready to continue the recipe stir in the baking powder and baking soda just before baking. This may make the cake a little more dense.

Pour cake batter into the greased sheet pan. Spread evenly with a spatula to fill the entire pan.

Bake and Cool the Cake

Bake for 22-24 minutes or until fully baked, avoid over-baking (if your pan is a different size bake time can vary).

When cake is baked completely a toothpick should come out clean and the center should look set. Take cake out of the oven and let cool in the pan for 15-20 minutes.

After slightly cooled, use a spatula to loosen the edges all around the cake. 

Place a piece of parchment paper on top then use hot pads to flip the pan so the parchment paper is now on the cooling rack with the pan bottom facing up. Tap the bottom of the pan to help loosen the cake and gently remove pan off the top. The cake should come right out. If it doesn’t, use your fingers to get an edge started. Let cool completely before frosting.

Make the Homemade Whipped Cream Frosting

While the cake cools, in a medium sized mixing bowl, add cold heavy whipping cream, vanilla extract, cane sugar, and softened cream cheese.

Use an electric mixer on medium speed to whip the ingredients together for 2-5 minutes until stiff peaks form (this means the whipped cream stays on the whisk and doesn’t drop off). Please be patient, it takes a little bit to thicken especially if you’re using organic heavy whipping cream. When it’s done set it in the fridge until the cake cools completely.

Decorate the Cake

Once cake is cooled, add all the whipped cream frosting to the top and spread with a butter knife to evenly coat the entire top, leave sides bare.

Rinse blueberries and raspberries with water and dry with a kitchen towel. Add blueberries in a rectangle to the top left of the cake for the blue star area. Place blueberries close together in the rectangle.

Add raspberries to make the stripes, I do 4 starting with one at the top, two in the middle, and one at the bottom of the cake. Stagger the raspberries so that the top of one raspberry is beside the bottom of the other, it makes a more solid stripe.

Use a butter knife to make a textured white stripe in the frosting between the rows of berries going horizontally across the cake.

This cake is best enjoyed immedietly but will last up to 3 days in the fridge. Store in an airtight container to prevent excessive drying out.

Variations

• Instead of raspberries, you can slice strawberries in half and use them instead.
• Add 1 tablespoon of lemon zest to the whipped cream frosting for more lemon flavor.
• Skip the lemon zest in the cake for a simple vanilla sourdough cake instead.

How to Serve

I recommend leaving this cake whole until you’re ready to enjoy it. Then slice it into as many pieces as you desire. For medium-sized slices, you’ll get about 12 servings.

My Tips

• Get the cream cheese out when you preheat the oven to ensure it’s softened when you make the frosting.
• You don’t have to get the eggs or dairy ingredients out for the cake. They work just fine if they’re cold in this recipe.
• Don’t over mix the cake batter once you’ve added the flour. It will make your cake dense.
• Make sure the heavy whipping cream comes straight from the fridge to the bowl; you don’t want it to warm up.

How to Store

Because this cake has whipped cream frosting, it needs to be refrigerated. This can cause the cake to dry out quickly if not stored correctly. I recommend eating it within 2-3 days.

You can get a large baking pan with a lid that the entire cake will fit down into. This is really great if you want to make it ahead. Or slice the cake up and store leftover slices in airtight glass containers.

Recipe FAQs

More 4th of July Recipes

• Sourdough Mason Jar Peach Trifles
• Homemade Tennessee BBQ Sauce
• Southern Banana Pudding
• American Flag Taco Dip

If you made this recipe, it would mean so much if you gave it a 5-star review below! Feel free to also share a photo on social media, tag @plumbranchhome. You can find our community on Instagram, Facebook, YouTube, and Pinterest

Recipe

Sourdough American Flag Cake

Molly LaFontaine

My sourdough American flag cake is made with from-scratch sourdough lemon sheet cake, homemade whipped cream frosting, and decorated with fresh berries. It's moist, light, and refreshing, making it the perfect 4th of July cake or summer dessert!

Print Recipe Pin Recipe

Prep Time 25 minutes mins

Cook Time 22 minutes mins

Cake Cooling 45 minutes mins

Total Time 1 hour hr 32 minutes mins

Course Dessert

Cuisine Sourdough

Servings 12 slices (medium sheet cake)

Ingredients

  

Sourdough Lemon Sheet Cake

• 1/3 cup avocado oil (or coconut oil, not olive oil)
• 3/4 cup raw cane sugar
• 2 large eggs
• 1 tsp pure vanilla extract
• 1/4 cup sourdough discard (fed starter works too)
• 3/4 cup milk (I use whole dairy milk)
• 1/2 cup sour cream (or plain unsweetened yogurt)
• 1/2 tsp sea salt
• 2 Tbsp lemon zest, packed into the measuring spoon
• 1 Tbsp lemon juice (fresh or pure bottled)
• 2 tsp baking powder (I use aluminum-free)
• 1/2 tsp baking soda
• 1 1/2 cup all-purpose flour (I use organic, unbleached)

Whipped Cream Frosting

• 1 cup heavy whipping cream (I use organic for no additives)
• 1 tsp pure vanilla extract
• 2 Tbsp raw cane sugar
• 2 oz plain cream cheese

Decorations

• 1 cup blueberries about 1/2 pint
• 2 cups raspberries about 1-2 pints

Instructions

 

• Preheat oven to 350 degrees Fahrenheit, get cream cheese out of fridge so it can warm for the frosting, and butter/flour a medium stainless steel rimmed sheet pan (approximately 12”x 9”). Set aside.

Make the Batter

• In a large mixing bowl add avocado oil and sugar. Mix with an electric mixer on low speed for 2 minutes.
• Add eggs one at a time. Mix each into the mixture on low speed until completely combined both times.
• Add in vanilla, sourdough discard, milk, sour cream, salt, lemon zest, lemon juice, baking powder, and baking soda (wait to add baking powder and baking soda if you’re doing the optional cold ferment step below). Mix on low-medium speed until everything is combined and no clumps are left, about 30 seconds.
• Add in flour and mix on medium speed JUST UNTIL combined. Do not over mix.
• Optional – At this point you can either continue the recipe or place the batter in the fridge, covered, for 12-24 hours to ferment for more sourdough fermentation benefits. When you’re ready to continue the recipe stir in the baking powder and baking soda just before baking. This may make the cake a little more dense.
• Pour cake batter into the greased sheet pan. Spread evenly with a spatula to fill the entire pan.

Bake & Cool

• Bake for 22-24 minutes or until fully baked, avoid over-baking (if your pan is a different size bake time can vary).
• When cake is baked completely a toothpick should come out clean and the center should look set. Take cake out of the oven and let cool in the pan for 15-20 minutes.
• After slightly cooled, use a spatula to loosen the edges all around the cake.
• Place a piece of parchment paper on top then use hot pads to flip the pan so the parchment paper is now on the cooling rack with the pan bottom facing up. Tap the bottom of the pan to help loosen the cake and gently remove pan off the top. The cake should come right out. If it doesn’t, use your fingers to get an edge started. Let cool completely before frosting.

Make the Frosting

• While the cake cools, in a medium sized mixing bowl, add cold heavy whipping cream, vanilla extract, cane sugar, and softened cream cheese.
• Use an electric mixer on medium speed to whip the ingredients together for 2-5 minutes until stiff peaks form (this means the whipped cream stays on the whisk and doesn’t drop off). Please be patient, it takes a little bit to thicken especially if you’re using organic heavy whipping cream. When it’s done set it in the fridge until the cake cools completely.

Decorate the Cake

• Once cake is cooled, add all the whipped cream frosting to the top and spread with a butter knife to evenly coat the entire top, leave sides bare.
• Rinse blueberries and raspberries with water and dry with a kitchen towel. Add blueberries in a rectangle to the top left of the cake for the blue star area. Place blueberries close together in the rectangle.
• Add raspberries to make the stripes, I do 4 starting with one at the top, two in the middle, and one at the bottom of the cake. Stagger the raspberries so that the top of one raspberry is beside the bottom of the other, it makes a more solid stripe.
• Use a butter knife to make a textured white stripe in the frosting between the rows of berries going horizontally across the cake.
• This cake is best enjoyed immedietly but will last up to 3 days in the fridge. Store in an airtight container to prevent excessive drying out.

Notes

• I don’t recommend making the frosting too far ahead, it’s best fresh.
• Heavy whipping cream must be cold, right out of the fridge, to make the frosting

Did you make this recipe? – If you loved it, I’d be so grateful if you left a comment on the blog post. It helps more than you know. You can share a photo on social media, tag @plumbranchhome

 

Sourdough Baking Disclaimer – I regularly feed my sourdough starter a 2:1 ratio of unbleached flour to filtered water, this creates a 50% hydrated starter even when I use discard. If you feed your starter differently, results may vary due to a different hydration which will cause a different consistency. No matter how you feed your starter just ensure it’s a thick consistency when you use it for my recipes, even if you’re using discard.

 

A Note From Molly – I NEVER use AI (artificial intelligence) to develop recipes or create content for plumbranchhome.com. What you see from PBH is real, made for a reason, tested, and loved.

 

Here at Plum Branch Home we’re serving God by loving our families one simple, wholesome, made from scratch recipe at a time!

Keyword sourdough american flag cake