Creating a Sour Cream Chocolate Cake is a straightforward process. Follow these steps to ensure your cake turns out perfectly:

1. Preheat the Oven: Set your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
2. Mix Dry Ingredients: In a large bowl, sift together the flour, sugar, cocoa powder, baking soda, baking powder, and salt.
3. Combine Wet Ingredients: In a separate bowl, whisk together the sour cream, vegetable oil, eggs, and vanilla extract until thoroughly combined.
4. Mix Dry and Wet Ingredients: Gradually add the wet mixture to the dry ingredients, stirring until just combined.
5. Add Boiling Water: Carefully mix in the boiling water. The batter will be thin, but this is normal.
6. Incorporate Melted Chocolate: If using, fold in the melted chocolate until evenly distributed.
7. Divide Batter: Pour the batter evenly into the prepared cake pans.
8. Bake: Place the pans in the preheated oven and bake for 30-35 minutes. A toothpick inserted in the center should come out clean.
9. Cool: Once baked, remove the pans from the oven and let them cool in the pans for about 30 minutes. Then, transfer the cakes to wire racks to cool completely.
10. Frost: Once cooled, you can frost the cake with your favorite chocolate frosting or whipped cream.
11. Dust with Powdered Sugar: For an elegant touch, dust the top with powdered sugar before serving.

By following these steps, you’ll create a rich and decadent Sour Cream Chocolate Cake that is sure to impress.