Using a hand mixer, combine butter and sugar together until white and fluffy. The butter will turn from yellow to white in color after about 2-3 minutes of being whipped with hand mixer.
Add in egg yolks one at a time. Add in vanilla extract (and almond extract if using) and sourdough discard. Blend until smooth.
To the wet mixture, Add salt and baking powder. Mix.
Add flour one cup at a time until combined. Do not overmix.
If fermenting on countertop, Cover tightly with plastic wrap or place in an airtight container. Allow to ferment 4-8 hours, or overnight. The goal is not for the dough to grow, this step is done to reduce the amount of phytic acid / gluten in the flour.
Place in the fridge for a bulk fermentation, up to 2 days. If skipping counter fermentation and / or bulk fermentation, follow baking instructions.
When baking sourdough sugar cookie crust, remove the sugar cookie dough from the refrigerator 30 minutes to 1 hour before baking. The dough will be softer when touched, like a tube of cookie dough.
Spread the cookie dough into two round 9” pans or two 9X13 glass rectangle pans. Using a fork, poke holes in the dough to allow steam to releasewhile cooking.
Cook at 350 degrees Fahrenheit for 10-12 minutes, or until the cookie is very slightly golden brown. The cookie will harden at room temperature. A softer cookie is better than hard!
While the cookie is baking, make the cream cheese frosting and wash/cut your berries. If you are using strawberries, remove the greens and cut in half.