Preheat your oven to 350°F (175°C) and grease two round cake pans.

In a bowl, whisk together flour, cocoa powder, baking powder, and salt.

In another bowl, beat eggs with granulated sugar until creamy; then mix in melted butter and orange zest.

Gradually combine dry ingredients with the wet mixture until just blended.

Pour the batter into prepared pans and bake for 25-30 minutes or until a toothpick comes out clean.

Allow cakes to cool before making the frosting by beating together softened butter, powdered sugar, heavy cream, and orange zest until fluffy.

Frost the cake generously between layers and on top.