01 -
Line three 6-inch pans with parchment paper on the bottoms. Preheat the oven to 350°F (180°C).
02 -
Combine the dry ingredients. Then mix in the cubed butter and cookie butter on low speed until it resembles coarse sand.
03 -
Mix in the sour cream and oil until just combined. It will form a thick paste. Scrape down the bowl, then on low speed, mix in the milk, eggs, and vanilla. Scrape down again and mix until smooth.
04 -
Pour half (about 210 g or 1 ½ cups) of the batter into each pan. Drizzle 1 tbsp melted cookie butter over the top of each. Spread the remaining batter evenly (another 210 g per pan).
05 -
Bake for 30-35 minutes. Cool the pans on a wire rack for 10 minutes, then remove the cakes and let cool completely.
06 -
Mix the butter and cookie butter together, then mix in the powdered sugar, heavy cream, and vanilla. Whip on medium-high speed for 2-3 minutes until light and fluffy.
07 -
Once the layers are completely cool, cut each in half horizontally if desired, or keep as three thick layers.
08 -
Place a dollop of buttercream on the serving platter. Place the first layer on top. Drizzle with 1-2 tsp melted cookie butter, then spread a thin layer of buttercream and sprinkle 1 tbsp cookie crumbs. Repeat this process, placing the last layer upside down for a flat top.
09 -
Apply a thin crumb coat of buttercream and chill until set.
10 -
Spread a thicker buttercream layer over the sides and top. Drizzle the remaining melted cookie butter over the top and sprinkle with cookie crumbs.