Creating Biscoff Speculoos Tiramisu is simple when you follow these steps:

1. Prepare Coffee Mixture: In a shallow bowl, combine the cooled brewed coffee and coffee liqueur (if using). Set aside.
2. Make Cream Mixture: In a large mixing bowl, beat the mascarpone cheese and Biscoff cookie spread until smooth and well combined.
3. Whip Cream: In another bowl, whip the heavy cream, powdered sugar, and vanilla extract until soft peaks form.
4. Combine Mixtures: Gently fold the whipped cream into the mascarpone mixture until fully incorporated.
5. Prepare Cookie Layers: Dip Biscoff cookies one at a time into the coffee mixture for about 2 seconds, ensuring they absorb the coffee but do not become soggy.
6. Layering: In a rectangular dish, arrange a layer of dipped Biscoff cookies at the bottom. Spread half of the cream mixture over the cookies.
7. Repeat Layers: Add another layer of dipped cookies, followed by the remaining cream mixture. Smooth the top with a spatula.
8. Chill: Cover the dish with plastic wrap and refrigerate for at least 4 hours, or overnight for the best flavor.
9. Garnish: Before serving, dust the top with cocoa powder or grated chocolate for an added touch.