Preheat your oven to 350°F (175°C). In a large mixing bowl, combine room temperature butter, zest from two oranges, and spices, whipping until creamy. Gradually add in the sugar, beating until pale and fluffy.

In a separate bowl, whisk together the flour, baking powder, and salt. Alternately add the dry ingredients and the buttermilk into the creamed mixture, stirring gently until just combined.

Line a cupcake pan with paper liners. Fill each liner halfway with the orange spice batter and bake for 18-20 minutes, or until a toothpick comes out clean.

Remove the cupcake pan from the oven and let it cool on a wire rack for about 5 minutes before transferring to cool completely.

In a saucepan, combine sugar and water, bringing it to a boil. Whip egg whites and cream of tartar in a stand mixer until stiff peaks form. Slowly add the hot syrup to the whipped egg whites, then gradually add the cocoa powder and butter, mixing until smooth.

In a medium saucepan, whisk together fresh orange juice, egg yolks, and sugar over medium heat until thick. Stir in butter until melted and smooth, then cool and refrigerate until set.

Once the cupcakes are cool, pipe the Chocolate Italian Meringue Buttercream on top, drizzle with orange curd, and garnish with zest ribbons and chocolate sprinkles.