Preheat the oven to 350℉. Spray three 8-inch cake pans with baking nonstick spray. Line the bottoms with parchment paper circles and spray again. Set aside.
In a medium bowl, sift the flour, baking powder, baking soda, and salt. Set aside.
3 1/2 cups All-purpose flour, 1 tsp Baking powder, 1/2 tsp Baking soda, 1 tsp Salt
Using a mixer, beat the butter, oil, and sugar on high speed for 2 minutes. It will be pale and fluffy. Scrape the bowl and add the vanilla, eggs, and sour cream. Mix on medium speed until combined.
1 cup Unsalted butter, 3 TBSP Oil, 1 1/2 cup White granulated sugar, 1 tsp Pure vanilla extract, 4 Large eggs, 3/4 cup Sour cream
Add in the dry ingredients and buttermilk. Mix on low speed until the cake batter is just combined. Take off the mixer and mix using a baking rubber spatula.
1 cup Buttermilk
Divide the batter evenly across the three cake pans. Place 5 frozen cookie dough discs per cake layer.
Bake for 26-32 minutes. Bake until a toothpick inserted comes out clean.
Let the cakes sit in the hot pans for 10 minutes before transferring to a cooling rack. Cool completely before decorating.