Preheat oven to 350°F.
In a bowl, whisk butter, sugar, eggs, flour, cocoa powder, and baking powder until smooth.
Add orange juice, zest, and beat until well combined.
In a baking pan pour the batter and place it into the oven for 20 minutes or until the cake tester comes out clean.
In a bowl mix the frosting and orange food coloring until uniform.
Remove cake from the oven, and let it cool for 30 minutes.
Decorate the cake with the frosting and cut into squares.
Serve and enjoy.