In a standing mixer cream your butter, shortening and sugar together until lighter in color and texture. This takes about 2 full minutes of whipping on high, scrapping down the bowl down every 30 seconds.
Add the extracts and stir until combined
Add the eggs and egg yolks, stir until just combined
In a separate bowl combine the flour, cornstarch, baking powder, and salt
Turn the standing mixer on low, slowly pour the dry ingredients in. As soon as the cookie dough comes together, stop the mixer.
Pour the evenly into five 9-inch cake pans that have been greased and lined with parchment paper.
Flatten the dough into the pan with a small roller or your hands
Bake for 20-25 minutes. Remove and allow to cool before frosting.
Frosting
In a standing mixer, add the cream cheese and butter. Mix on low until the two are combined and slightly softened.
Add the sugar and extracts, mix on low until the frosting is combined.
Slowly increase the speed until your mixer is on high. Whip the frosting on high for 1-2 minutes until lighter in color and texture.
Add food coloring if you desire.
Assemble
Once the cake is cooled, place one of the 9-inch cookie cakes on a cake cardboard round or platter. Spread a generous frosting on top. Place another cookie cake on top and repeat until all 5 cookie cakes have been used.
Spread the remaining frosting around the outside of the cookie cake to make a thin, see-through layer. Top with sprinkles if you'd like.
Place in the fridge for at least 1 hour to set before serving.