Birthday Brownies, easy from scratch chocolate cake like brownies topped with a simple homemade white buttercream frosting and colorful jimmies sprinkles.
In another bowl, whisk together melted butter and granulated sugar. Whisk the eggs, milk, and 1 teaspoon vanilla until well combined. Gently whisk in the flour mixture until just combined.
When brownies are cool, start frosting. In a large mixing bowl, beat together softened butter and powdered sugar with an electric mixer on medium speed.