Preparation:

Step 1: Prepare the Chocolate Cake Layers

1. Preheat the oven to 350°F (175°C). Grease and flour two 8-inch round cake pans.
2. In a large bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.
3. Add the eggs, milk, vegetable oil, vanilla extract, orange juice, and orange zest. Mix until smooth and well-combined.
4. Divide the batter evenly between the two prepared pans.
5. Bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean.
6. Let the cakes cool completely before assembling.

Step 2: Make the Orange Cheesecake Layer

1. Lower the oven temperature to 325°F (165°C). Line an 8-inch cake pan with parchment paper.
2. In a mixing bowl, beat the cream cheese and sugar until smooth and creamy.
3. Add the egg, sour cream, orange juice, and orange zest, mixing until fully combined.
4. Pour the cheesecake batter into the prepared pan.
5. Bake for 30-35 minutes, or until the center is set.
6. Let the cheesecake cool completely, then chill in the refrigerator for at least 1 hour.

Step 3: Assemble the Cake

1. Place one cooled chocolate cake layer on a serving plate or cake stand.
2. Carefully place the chilled cheesecake layer on top of the chocolate cake layer.
3. Add the second chocolate cake layer on top of the cheesecake.

Step 4: Make the Chocolate Ganache

1. In a microwave-safe bowl, heat the heavy cream until warm (but not boiling).
2. Pour the warm cream over the chocolate chips and let it sit for 1-2 minutes.
3. Stir the mixture until smooth and glossy.
4. Let the ganache cool slightly until it thickens but is still pourable.

Step 5: Top with Ganache

1. Pour the ganache over the assembled cake, allowing it to drip down the sides for a decorative finish.
2. Use a spatula to spread the ganache evenly over the top of the cake.