Melt ½ stick of butter
Add ⅓ cup of dry milk powder
Toast the mixture until it's really dark brown
Add ⅔ cup of heavy cream to stop the cooking process
In a stand mixer, mix 2 sticks of room temperature butter, salt, and vanilla until smooth and creamy
Sift 1 pound of powdered sugar and add half of it to the mixer, pulsing to combine
Add the browned butter mixture and the other half of the powdered sugar, mixing on high until a luxurious plush buttercream forms
Spread the buttercream generously over a chocolate sheet cake, pushing it into the corners
Optionally, add sprinkles
