Preheat your oven to 350°F (175°C). Line an 8x8-inch baking pan with parchment paper. In a large mixing bowl, combine the softened butter, granulated sugar, and brown sugar, mixing until smooth.

Add the eggs and vanilla extract, and whisk until fully incorporated.

In a separate bowl, whisk together the cocoa powder, flour, baking powder, and salt.

Gradually add the dry ingredients to the wet ingredients, stirring until the batter is smooth and thick.

Pour the batter into the prepared pan and spread it evenly with a spatula.

Bake for 25–30 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs (not wet batter).

Keep a close eye towards the end to avoid overbaking. The brownies should be soft and chewy.

Once baked, remove from the oven and allow them to cool in the pan for 10-15 minutes before transferring to a wire rack.

While the brownies are cooling, prepare the chocolate frosting. In a bowl, mix powdered sugar, cocoa powder, softened butter, and a little milk until smooth and creamy. Adjust the consistency by adding more milk if needed.

Once the brownies are completely cooled, spread a generous layer of frosting evenly over the top.

Allow the frosting to set for about 10–15 minutes.

Cut the brownies into squares using a sharp knife.

Serve immediately, or store them in an airtight container at room temperature for up to 3-4 days.