In a large mixing bowl, combine gluten-free flour, cocoa powder, granulated sugar, and espresso powder. Stir well to evenly distribute the dry ingredients. Then, add melted butter and eggs into the dry mixture, and whisk together until the batter is smooth and glossy, approximately 3-4 minutes.

Preheat your oven to 350°F (175°C). Grease a 9x9-inch baking pan with butter or cooking spray, then pour the batter into the pan, spreading it evenly. Bake for 25 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs. Allow them to cool in the pan for at least 10 minutes before transferring to a wire rack to cool completely.

While the brownies are cooling, prepare the tiramisu layer. In a medium bowl, combine mascarpone cheese, whipping cream, sugar, and vanilla extract. Using an electric mixer, whip the mixture on medium speed until it becomes smooth and creamy, about 3-5 minutes.

Once the brownies have completely cooled, gently spread the mascarpone mixture evenly over the top of the brownie base using a spatula.

Cover the assembled brownies with plastic wrap and refrigerate for at least 2 hours.

Before serving your delicious Gluten Free Tiramisu Brownies, dust the top generously with cocoa powder using a fine sieve for a classic finish. Slice the brownies into squares with a hot knife for clean edges.