Preheat oven to 350°F (175°C). Grease and flour a 9-inch round cake pan or line it with parchment paper.
2. Make the Cake Batter
In a medium bowl, whisk together flour, baking powder, baking soda, and salt.
In a large bowl, beat butter, Biscoff cookie butter, and brown sugar until creamy.
Add eggs one at a time, then stir in vanilla extract.
Alternately add dry ingredients and buttermilk, starting and ending with the dry ingredients.
Fold in sour cream until the batter is smooth.
3. Bake the Cake
Pour batter into the prepared pan and smooth the top. Bake for 35–40 minutes, or until a toothpick inserted comes out clean. Let cool completely before frosting.
4. Make the Frosting
Beat butter and Biscoff cookie butter until creamy. Gradually add powdered sugar, then vanilla and heavy cream, until smooth and spreadable.
5. Assemble & Serve
Frost the cooled cake with Biscoff frosting. Optionally, top with crushed Biscoff cookies or drizzle with caramel. Slice and enjoy with a cup of coffee or tea.
Serving and Storage Tips
