Preheat oven to 375°F. Line a baking sheet with parchment paper or a baking mat. Set aside.
In a large bowl, or the bowl of a stand mixer, cream the butter, cookie butter, brown sugar, and granulated sugar, about 2-3 minutes on medium speed.
Add egg and vanilla and mix until well combined. Scrape down the sides of the bowl as needed.
Add baking soda, baking powder, salt, flour, ½ cup finely ground Biscoff cookie crumbs, oats, and mix until just combined. Add the white chocolate chips and the Biscoff chunks and mix until combined
Portion into 1/3 cup sized balls, place on baking sheet and press down on the balls with your palm to slightly flatten the tops. Bake for 8-9 mins or until the edges are just barely set but the centers are still soft and slightly shiny.
Remove cookies from the oven and top with a Biscoff cookie piece. Let them cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool slightly.
Serve at room temperature or warm. Store in an airtight container at room temperature for 3 days.