Creating these delightful tiramisu brownies can be quite simple if you follow these steps:

1. Preheat Oven: Set your oven to 350°F (175°C). Grease a 9×9-inch baking pan.
2. Make Brownie Batter: In a saucepan, melt the butter over low heat. Once melted, remove from heat and stir in the sugar until well combined.
3. Add Eggs and Vanilla: Beat in eggs, one at a time, followed by the vanilla extract until fully incorporated.
4. Combine Dry Ingredients: In a separate bowl, sift together flour, cocoa powder, baking powder, and salt.
5. Mix Dry and Wet Ingredients: Gradually add the dry mixture to the wet mixture, stirring until just combined.
6. Bake Brownies: Pour the batter into the prepared pan and spread evenly. Bake for 25-30 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs.
7. Cool Brownies: Once baked, allow the brownies to cool completely in the pan on a wire rack.
8. Prepare Tiramisu Layer: In a bowl, combine mascarpone, heavy whipping cream, powdered sugar, and coffee liqueur. Whip until soft peaks form.
9. Soak Brownies: Once cooled, remove brownies from the pan and cut them into squares. Dip each square briefly into the cooled coffee to soak (but do not oversoak).
10. Layer Assembly: In a serving dish or individual glasses, layer soaked brownies with the tiramisu cream. Repeat until all components are used.
11. Chill: Refrigerate assembled brownies for at least 2 hours to set.
12. Dust and Serve: Just before serving, dust the top with cocoa powder for a beautiful finish.