Preheat the oven to 350°F. Prepare a 9x13-inch baking dish by lining it with foil and spraying it with non-stick cooking spray. In a mixing bowl, combine the cocoa powder and melted butter, beating with an electric mixer until smooth. Add the flour and sugar, continuing to mix until fully combined. Then, incorporate the eggs and vanilla, mixing until just combined; be careful not to overmix, as the batter will be thick.

Transfer the thick batter into the prepared baking dish, spreading it evenly. The dense consistency may require a moment to fully spread. Bake for 25 to 30 minutes, or until a fork inserted into the center comes out clean. Baking times may vary depending on your oven, but 30 minutes should be ideal.

Allow the brownies to cool for about 15 minutes before frosting. The brownies should still be warm when you apply the frosting.

Frosting Instructions

In a separate bowl, beat together the evaporated milk, softened butter, powdered sugar, and cocoa powder until smooth and creamy. Once the frosting is ready, pour it over the warm brownies and spread evenly. Allow the brownies to cool completely before cutting into squares. If the frosting is too thick, adjust the consistency with a small amount of additional milk to achieve the desired texture before spreading.