Preheat your oven to 350°F (175°C). Grease and line two 8-inch round cake pans with parchment paper.
In a medium bowl, whisk together flour, baking powder, baking soda, and cinnamon or nutmeg until combined.
In a large mixing bowl, beat butter and sugar with an electric mixer until pale and fluffy.
Add eggs one at a time, beating after each addition. Mix in the vanilla extract.
Alternate adding the dry ingredients and milk to the butter mixture, beginning and ending with dry. Mix gently until just combined.
Fold in the Biscoff cookie butter, swirling it gently into the batter for even flavor.
Divide the batter evenly between the prepared pans. Bake for 25–30 minutes, or until a toothpick inserted into the center comes out clean.
Let the cakes cool in the pans for 10 minutes, then transfer to a cooling rack to cool completely.
For the frosting, beat cream cheese or buttercream with powdered sugar until smooth. Add cookie butter and beat until creamy and spreadable.
Assemble the cake by spreading frosting between layers and over the top. Decorate with crushed cookies, nuts, caramel drizzle, or berries.
