Step 1: In a large mixing bowl, beat the room temperature mascarpone cheese and Biscoff spread together until smooth and well combined.
Step 2: In a separate chilled bowl, whip the heavy cream, powdered sugar, and vanilla extract until stiff peaks form.
Step 3: Gently fold the whipped cream into the Biscoff-mascarpone mixture in three batches, being careful not to deflate the air.
Step 4: Briefly dip each ladyfinger into the cooled coffee (about 1 second per side) and arrange them in a single layer at the bottom of an 8×8 inch dish.
Step 5: Spread half of the Biscoff cream mixture over the first layer of ladyfingers, smoothing it out with a spatula.
Step 6: Repeat with another layer of coffee-soaked ladyfingers and the remaining cream mixture.
Step 7: Cover and refrigerate for at least 6 hours, preferably overnight, to allow the cookies to soften and flavors to develop.
Step 8: Just before serving, sprinkle the crushed Biscoff cookies over the top for a crunchy finish.