Preheat your oven to 350°F (175°C) and grease two round cake pans.
In a large bowl, whisk together flour, cocoa powder, baking powder, and sugar.
In another bowl, mix eggs, melted butter, milk, and orange zest until smooth.
Pour the wet mixture into the dry ingredients and stir until just combined.
Divide batter evenly between pans and bake for 25–30 minutes or until a toothpick comes out clean.
Allow cakes to cool before preparing the glaze by mixing powdered sugar with fresh orange juice until smooth.
Layer the cakes with glaze in between and drizzle remaining glaze on top.