• 30 minutes to 1 hour before you start this recipe set out butter, eggs, sourdough discard, milk, sour cream, and cream cheese so they can come to room temperature.

Make the Cake

• Preheat oven to 350 degrees and grease a (approximately 10” x 15”) rimmed baking sheet pan (AKA a jelly roll pan) with butter and flour (tap off extra flour).
• 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.
• Add eggs one at a time, beating until completely combined both times.
• Add in vanilla, sourdough discard, milk, sour cream, salt, and baking powder. (IMPORTANT: if you want to make the batter ahead or do the optional cold ferment in a few steps, wait to add baking powder!) Mix on low-speed just until combined. Do not over mix.
• Add in flour a little at a time and mix on low speed just until combined. Do not over mix.
• OPTIONAL: You don't have to do this step but you can add an airtight lid to the mixing bowl or Saran Wrap and place it in the fridge for up to 24 hours until you’re ready to bake. This allows the starter’s cultures to ferment the other ingredients adding more fermentation benefits. If you do this step, add baking powder right before baking.
• Pour cake batter onto the prepared baking sheet. Spread evenly with a spatula to fill the entire pan.
• Bake for 20-24 minutes or until a toothpick comes out clean.
• Take cake out of oven and place, still in the pan, on a wire rack for 30 minutes to cool. 

Make the Whipped Cream Layer

• During this cooling time, in a medium sized mixing bowl, add cold heavy whipping cream, vanilla extract, softened cream cheese, and powdered sugar.
• Use an electric mixer on medium speed with a whisk attachment (or a regular whisk if desired) to whip the ingredients together for 2-3 minutes or until peaks form. The whipped cream should stay on the whisk and not drop off. Store in the fridge until you’re ready to use it.

  (If heavy whipping cream isn’t cold the whipped cream won’t come together. If this happens place the bowl in the freezer for 5-10 minutes and try again.)

Melt Chocolate for Decorating

• Fill a pot about 1/3 of the way full with water and bring to a simmer over medium-high heat.
• Once simmering turn down heat to medium-low and place a glass or stainless steel heat-safe bowl over the pot. It should sit on the pot but ensure the bottom doesn't touch the water.
• Add chocolate chips of choice (semi-sweet or white) to bowl and melt over medium-low heat, stirring continuously until smooth. Carefully use hot pads to immediately take bowl off heat as soon as it's melted. Do not let chocolate burn.

Cut the Cake

• When cake is fully cooled, take a spatula and loosen edges as well as underneath the cake. Be very gentle not to crack the cake.
• Place a cutting board on top of the pan and flip the entire board and pan upside down so the pan is sitting on the board. Remove pan and cake should come out easily onto the board if you loosened it all the way.
• Leave cake upside down and take a 4” Christmas tree cookie cutter and cut out trees. Start close to the edges so you can cut a few out of the center.
• Set excess cake aside (you can use this for another recipe like cake pops, or you can cut it up and save it or freeze it for later).

Assemble and Decorate

• Spread 2-3 spoonfuls of the whipped cream filling you made on half of the trees. The other half will be used to top them. Make sure you have a good ratio of filling to cake.
• Place other half of uncovered trees on top of the covered to make little 2-tiered cakes.
• To decorate, grab the chocolate you melted earlier (if it's hardened warm it back up over the pan) and spread an even layer over the tops of each tree.
• Once you’ve "frosted" your trees immediately sprinkle tops with decorating sugar.
• Place decorated trees on a clean parchment-lined sheet pan and refrigerate for 5-20 minutes to harden chocolate. Enjoy!
• Be sure to store leftover cakes in an airtight container in the fridge.