Instructions

Chocolate Sourdough Discard Cake layers

• Preheat an oven to 350 degrees F (180C) or 325 F (160C) for a convection oven. Grease 3 8-inch cake pans with baker's floured spray (or line with silicone or parchment rounds).
• Mix together all dry ingredients (flour, sugar, cocoa powder, baking soda, and salt) in a stand mixer with a paddle until fully combined.
• Mix chunks of room-temperature butter slowly into the dry mix, on a low speed. Continue to mix until no large chunks of butter remain, and the mixture becomes crumbly. Add oil and mix until well combined.
• Pour in eggs and mix on low until just combined (the mixture will be thick at this stage; this is normal). Whisk together sourdough discard, milk, and vanilla until well-combined. Add the sourdough discard mixture in 2 parts, mixing until combined.
• Scrape down the sides of the bowl with a spatula, then beat on medium speed for about 30 seconds.
• Divide batter evenly between the prepared cake pans. (I find a kitchen scale helpful for this part, and had about 650g in each pan; this guarantees your layers will bake to be the same height.)
• Bake for 32-37 minutes (or until a toothpick comes out clean). Allow cake layers to cool for 10-15 minutes on a wire cooling rack before removing from pans – it helps to run an offset spatula or knife around the perimeter of the pan first. Cool completely before frosting. Set in the fridge or freezer to accelerate the cooling process if desired.
• This is a great time to make your frosting!

Chocolate Cream Cheese Buttercream Frosting

• Beat together softened cream cheese and butter; slowly add in powdered sugar alternating with flavoring until frosting reaches desired consistency. Add vanilla and salt/milk if needed and beat until well combined.

Assembly

• If needed, once cake layers are cooled, level them (These generally bake pretty flat and I don’t trim much from the tops). This can be done with a cake leveler or a large serrated knife and a ruler.
• Place a smear of frosting on your cake circle (to keep the cake from sliding while you decorate it) and center your first cake layer in the center of the circle.
• Spread the first layer with frosting. Add your next cake layer on top, and repeat the process with your remaining cake layers.
• Now you're ready to frost - I’ve started using a cake ring at this stage - more in this video or this post. Otherwise - if using the traditional method you’re ready to crumb-coat. If you're unfamiliar with crumb-coating, it's just what it sounds like – spreading a thin layer of frosting over the entire outside of the cake to keep crumbs out of your final layer.
• Once your crumb coat has set (this takes about 5-10 minutes in the fridge), add your final layer of frosting and smooth. (See this post for help if needed.)

Decorating

• The smoothing motion around the sides will probably result in a small ‘lip’ or ‘ridge’ of frosting at the top – this is a good thing. ;) Wipe off the offset spatula, and use it to pull in that ‘lip,’ keeping the spatula even with the top of the cake. Work your way around the cake until the top edge is smooth. Smooth-ish. Whatever. ;)
• Feel free to decorate however you'd like - sprinkles and frosting swirls like I did, or berries or even edible flowers ;)

  Annnd you’re done! Cut in and enjoy! Congrats on your killer sourdough discard cake!