Crust

1. To make the crust, crush the Biscoff cookies until the consistency of rough sand. Stir in melted butter and toss until well incorporated.
2. Divide mixture in a mini muffin pan (about 1 1/2 teaspoons each) and press in firmly (use a shot glass or a muddler). Set aside

Filling

1. Add the cream cheese to the base of a stand mixer fitted with a paddle attachment (or use an electric hand mixer and medium bowl). Mix until light and fluffy, about 2 minutes. Add cookie butter and mix until well incorporated. Add the sour cream, sifted powdered sugar and vanilla and mix until smooth.
2. Transfer mixture to a piping bag or a ziptop bag with one end snipped off. Pipe the filling evenly into the mini muffin pan (there is enough filling to come almost to the top of all muffin openings). Gently smooth the top with damp fingers then cover with plastic wrap and freeze for at least 1 minute.

Topping

1. Stir together cookie butter and milk or heavy cream until smooth and slightly runny (you may need to add a bit more dairy to adjust consistency). Remove the cheese cakes from the pan and dip the tops of the cheesecakes into the cookie butter topping. Sprinkle with crushed cookies and serve immediately.