Preheat your oven to 350°F (175°C) and prepare three 8-inch cake pans. Line them with parchment paper and grease the sides with butter or cooking spray. This crucial step will make it easier to release the cakes once they’re baked.

Grab a large mixing bowl and combine the flour, cinnamon, baking powder, and salt. Using a mixer, blend the dry mixture with softened butter until it forms a crumbly texture. This will set the base for soft, tender cake layers.

Next, whisk in the egg whites. Pour in the buttermilk and vanilla extract gradually, mixing as you go. Scrape down the sides of the bowl to ensure the batter is well combined and free of lumps. The result should be a smooth, creamy mixture.

Divide the batter evenly into your prepared cake pans. Bake them for 33-35 minutes, rotating the pans halfway to ensure even cooking. Once done, allow the cakes to cool completely before moving on to the frosting.

While the cakes cool, whip the unsalted butter, powdered sugar, and heavy cream together to create a fluffy vanilla frosting. Scoop out a portion and blend it with cookie butter for a deliciously rich twist. This will be your secret weapon for those irresistible layers.

Alternate the vanilla and cookie butter frosting between the layers, spreading evenly with an offset spatula. Drizzle warm cookie butter over each layer to deepen the flavor. Finally, press crushed Biscoff cookies onto the sides for a decorative touch.

Chill the finished cake in the fridge for 20 minutes. This helps the frosting firm up and makes slicing easier. Once ready, bring it out, and brace yourself for the compliments!