Step 1: Brew 300ml of strong espresso or coffee and pour it into a wide, shallow bowl. Let it cool completely to room temperature.
Step 2: In a small microwave-safe bowl, melt 100g of the Biscoff spread for 20 seconds until it reaches a pourable consistency. Set aside.
Step 3: In a large mixing bowl, beat the mascarpone cheese, powdered sugar, vanilla extract, and the remaining 100g of Biscoff spread until smooth and creamy.
Step 4: In a separate chilled bowl, whip the heavy cream until stiff peaks form. Carefully fold the whipped cream into the mascarpone mixture in three batches to keep the filling light.
Step 5: Quickly dip the Biscoff cookies into the cooled coffee (about 1 second per side) and arrange them in a single layer at the bottom of an 8x8 inch glass dish.
Step 6: Spread half of the mascarpone cream mixture over the cookie layer. Drizzle half of the melted Biscoff spread over the cream.
Step 7: Add a second layer of coffee-dipped cookies, followed by the remaining mascarpone cream. Smooth the top with a spatula.
Step 8: Drizzle the remaining melted Biscoff spread on top and sprinkle with crushed Biscoff cookie crumbs. Cover and refrigerate for at least 6 hours or overnight before serving.