Begin by crushing about 24 Biscoff cookies into fine crumbs using a food processor or rolling over them in a zip-lock bag.

Melt 4 tablespoons of butter and mix with 2 tablespoons of cookie butter until smooth. Stir in cookie crumbs until coated.

Transfer the crumb mixture into a 9-inch tart pan and press it evenly across the bottom and up the sides to form a crust. Chill in the refrigerator for at least 15 minutes.

Heat 1 cup of heavy cream in a saucepan until it simmers. Pour it over chopped chocolate in a bowl and let sit for 3-5 minutes before stirring until smooth.

Pour the chocolate ganache into the chilled crust and spread it evenly to the edges.

Cover the tart and chill in the refrigerator for at least 4 hours or overnight to set.

Before serving, let the tart sit at room temperature for 10 minutes, then slice and garnish as desired.