Crush the 3 Biscoff cookies in a food processor or blender. Preheat oven to 350 degrees. Use parchment paper or a silpat mat to line a baking sheet.
Cream the butter, cookie butter, brown sugar and sugar in a stand mixer until light and fluffy (about 2-3 minutes). Scrape the sides of the bowl to make sure all ingredients are blended.
Add in the egg and vanilla and beat until combined.
Add in flour, CRUSHED Biscoff Cookies, baking soda, baking powder and salt. Stir until all combined.
Stir in white chocolate chips.
Scoop out about 1/4 cup of dough for smaller cookies (or 1 TBSP dough for mini cookies). Place dough balls on plate or baking sheet. Freeze dough balls for 10 minutes.
Place the frozen cookie dough balls on the prepared baking sheet (9 cookies to a pan if big cookies and 12 to a pan if small cookies).
Bake for about 11-12 minutes (if making big cookies!). Remove from oven. Press half of a Biscoff cookie into the cope of each cookie and let cool on tray for 10 minutes. Transfer cookies to cooling rack. NOTE: Baking time will be shorter (8-9 minutes) if you make mini cookies.