Preheat your oven to 350 F. Grease two 8-inch round cake pans and line the bottoms with parchment paper.
Whisk together the almond flour, gluten free flour, baking powder, baking soda, cinnamon, and salt in a medium bowl.
In a large bowl, whisk the cookie butter and brown sugar together until smooth. Add the eggs one at a time, whisking well after each. Stir in the sour cream, oil, and vanilla until combined.
Pour the dry ingredients into the wet and fold until just combined. Divide the batter evenly between the two prepared pans. Bake for 25 to 30 minutes until a toothpick inserted in the center comes out clean. Let the cakes cool in the pans for 10 minutes, then turn them out onto wire racks to cool completely.
Make the frosting by beating the softened butter and cookie butter together until creamy and smooth, about 2 minutes. Gradually add the powdered sugar, one cup at a time, beating on low speed. Add the heavy cream and salt, then increase the speed to medium-high and beat for 2 to 3 minutes until light and fluffy.
Place one cake layer on your serving plate. Spread a thick layer of frosting on top. Place the second layer on top and frost the top and sides of the entire cake with the remaining frosting.
Press crushed gluten free Biscoff cookies around the bottom edge and sprinkle more on top. Refrigerate for 30 minutes to set the frosting before slicing.