Preheat the oven: Set your oven to 350°F (175°C) and line an 8x8-inch baking pan with parchment paper for easy removal.

Prepare the brownie base: In a medium bowl, whisk together the melted butter and granulated sugar until smooth. Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.

Mix dry ingredients: In a separate bowl, sift together the flour, cocoa powder, baking powder, and salt. Gradually fold the dry ingredients into the wet mixture, stirring until just combined.

Add chocolate chips: Gently fold in the chocolate chips for that extra layer of richness.

Bake the brownie base: Pour the batter into the prepared pan and spread it evenly. Bake for 20-25 minutes or until a toothpick inserted into the center comes out with just a few moist crumbs. Allow the brownies to cool completely in the pan.

Make the mascarpone topping: While the brownies cool, whisk together the mascarpone cheese, powdered sugar, and vanilla extract until smooth and creamy. Add the cooled espresso and mix until fully incorporated.

Assemble the brownies: Once the brownies are cool, spread the mascarpone mixture evenly over the top, creating a creamy layer.

Chill and serve: Refrigerate the brownies for at least 2 hours to let the flavors set. Before serving, dust the top with a light sprinkle of cocoa powder for an extra touch of elegance.