Preheat the oven to 350°F/177℃. Grease and parchment line a 8.5x4.5” or 9x5" loaf pan with overhangs for easy removal (one down the length, one down the width).
Combine the orange zest and sugar, rubbing it together with your fingers for about one minute until it turns orange.
2 large oranges, 1 cup granulated sugar
In a large bowl, whisk together the flour, cocoa powder, baking powder and salt.
1¼ cup all purpose flour, ½ cup dutch processed cocoa powder, 2 teaspoons baking powder, ¼ teaspoon kosher salt
In other bowl, whisk together the eggs and sugar until combined, frothy, and slightly airy.
2 large eggs
Add in the melted butter, oil, and buttermilk and whisk to combine.
6 tablespoons unsalted butter, ½ cup buttermilk, ¼ cup vegetable oil
Pour the wet ingredients into the dry ingredients and stir and fold together with a rubber spatula or wooden spoon. Once combined, add in the hot coffee and carefully mix until completely combined.
¼ cup hot coffee or water
Add the batter to the prepared pan and bake for 30-45 minutes or until a toothpick inserted into the center comes out clean. Allow it to cool for 15 minutes in the pan, then remove and transfer to a wire rack to finish cooling.
While the cake bakes, heat the heavy whipping cream and add it on top of the chopped milk chocolate. Allow it to stand for 1 minute, then mix until smooth. Add the orange extract and stir to combine.
12 oz milk chocolate, 1 cup heavy whipping cream, 2 teaspoons orange extract
Transfer it to the fridge or freezer and allow it to set, stirring every 5 minutes until thick, creamy, and spreadable. Then, allow it to sit at room temperature.