01 - Preheat oven to 350°F. Line an 8x8-inch baking pan with parchment paper, allowing overhang for easy removal.
02 - Whisk melted butter and sugar in a large bowl until combined. Add eggs and vanilla; whisk until smooth.
03 - Sift cocoa powder, flour, salt, and baking powder into the bowl. Fold gently with spatula until just combined.
04 - Pour batter into prepared pan, smooth top. Bake 28-32 minutes until toothpick inserted in center has moist crumbs.
05 - Beat softened butter with powdered sugar until fluffy. Add milk, vanilla, and food coloring; beat until smooth and pink.
06 - Cool brownies completely. Spread frosting evenly over top. Cut into squares and serve.