- Place a rack in the middle of your oven and preheat oven to 325ºF.
- Grease and flour a mini Bundt cake pan, making sure to cover all nooks and crannies of the pan.
- Blitz your Biscoff cookies in a food processor until powder-like in texture and appearance.
- In a large bowl, whisk together flour, ground Biscoff cookies, cinnamon, baking soda, baking powder, and salt.
- In a second bowl, whisk together the eggs, brown sugar, sour cream, cookie butter, oil, and vanilla.
- Add the wet ingredients to the dry, and mix until just combined.
- Chop your apples, then gently fold them into your batter until incorporated.
- Spoon batter into your greased and floured mini Bundt cake pan until approximately 3/4 full.
- Bake for about 20 minutes, or until a toothpick inserted in the middle of the cakes comes out clean.
- Let the cakes cool in the pan on a rack for 10 minutes. Invert the cakes onto a wire rack and let cool completely.
Optional: Add the warm glaze with cookie crumbs on top of these mini cakes for extra flavor and texture!