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–+ servings
sourdough vanilla half sheet cake freshly baked
Molly LaFontaine

Sourdough Vanilla Half Sheet Cake

This sourdough vanilla half sheet cake is so versatile! You can use it during the holidays to make homemade Christmas tree cakes or trifle desserts during summer. It's also a great snack cake for birthdays or when you get a cake craving!
My husband and I love this cake in many recipes. It's not overly sweet and the batter can be fermented overnight. I hope this recipe replaces vanilla box cake mix for you just like is has for us!
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Prep Time 10 minutes
Cook Time 20 minutes
Total Time 30 minutes
Servings: 1 half sheet cake
Step-By-Step Mode

Ingredients
  

  • 6 Tbsp softened butter (I like to use salted)
  • 2 tsp avocado oil
  • 3/4 cup pure cane sugar (granulated)
  • 2 eggs (room temperature)
  • 1 tsp pure vanilla extract
  • 1/2 cup sourdough discard (aka unfed starter)
  • 3/4 cup milk (slightly warmed, not hot)
  • 1/4 cup sour cream
  • 1/4 tsp salt
  • 2 tsp baking powder
  • 1 1/2 cup all-purpose flour

Instructions

  1. Preheat oven to 350 degrees Fahrenheit. Grease and flour a rimmed half sheet pan (about 10"x15")
Make the Batter
  1. In a large mixing bowl add softened butter, avocado oil, and sugar. Mix with an electric mixer (with beater attachments) on low speed for 2 minutes. It should be creamy and well-combined.
  2. Add eggs one at a time. Beat each into the mixture on low speed until completely combined both times.
  3. Add in vanilla, sourdough discard, milk, sour cream, salt, and baking powder (wait to add baking powder if you’re doing the optional cold ferment step below). Mix on low speed just until combined. Do not over mix.
  4. Add in flour (a little at a time) and mix on low speed just until combined. Do not over mix.
  5. Optional – At this point you can either continue the recipe or place the batter covered in the fridge for 12-24 hours to long ferment for more sourdough fermentation benefits. When you’re ready to continue the recipe stir in the baking powder just before baking.
  6. Pour cake batter onto the prepared baking pan. Spread evenly with a spatula to fill the entire pan.
Bake & Cool
  1. Bake for 20-24 minutes or until a toothpick comes out clean. (If you pan is differently sized please adjust your bake time a few minutes.)
  2. Take the cake out of the oven and let cool in the pan for 5 minutes.
  3. Then use a spatula to loosen the edges of cake around the pan.
  4. Place a piece of parchment paper on top of the cake in the pan. Then place a cooling rack over the top of that so it’s laying right side up on the parchment paper.
  5. Flip the entire thing upside down so that the wire rack is standing on the counter like it should. Remove the pan and your cake should come right out. Let cool completely before frosting and enjoy!

Notes

This recipe makes a short 10"x15" half sheet cake. For a thicker sheet cake use a smaller pan.

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.
This recipe was developed from scratch in my kitchen by me, Molly LaFontaine, and tested many times to ensure success. Just like all of my recipes on Plum Branch Home. They're created with purpose, cherished in our own home, and developed with my experiences, trial and error, and skills. NEVER AI (artificial intelligence). 
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