Directions:
Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans and line the bottoms with parchment paper. Grease and line a 9-inch springform pan for the cheesecake layer.
For the chocolate cake layers, in a large bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt. Add the buttermilk, vegetable oil, eggs, and vanilla extract. Beat on medium speed until well combined. Stir in the hot water until the batter is smooth. Divide the batter evenly between the two prepared cake pans.
Bake the chocolate cake layers for 30-35 minutes, or until a toothpick inserted into the center comes out clean. Let the cakes cool in the pans for 10 minutes, then transfer to a wire rack to cool completely.
For the orange cheesecake layer, beat the cream cheese and sugar together in a large bowl until smooth. Add the orange zest and vanilla extract, mixing until combined. Beat in the eggs one at a time, mixing well after each addition. Pour the cheesecake batter into the prepared springform pan.
Bake the cheesecake layer for 40-45 minutes, or until the center is set. Allow the cheesecake to cool completely in the pan, then refrigerate for at least 2 hours.
For the chocolate ganache, place the chocolate chips in a heatproof bowl. Heat the heavy cream until just boiling, then pour over the chocolate chips.