Preheat your oven to 350 degrees Fahrenheit.
Spray a 12-15 cup non-stick bundt cake pan with non-stick cooking spray. Dust it lightly with flour and cocoa powder (use about 1/2 tablespoon of each), then shake out any excess.
In a medium mixing bowl, whisk together the flour, granulated sugar, baking soda, and salt. Set this dry mixture aside.
In a large mixing bowl, whisk together the melted butter, hot water, and cocoa powder until well combined.
Add the dry flour mixture to the butter mixture, and use an electric hand mixer to blend everything until it's well combined.
Add the sour cream, eggs, and vanilla extract to the mixture, and mix until everything is well combined.
Pour this mixture into the prepared bundt pan.
Bake in your preheated oven for approximately 40 to 50 minutes or until a toothpick inserted into the center comes out clean.
Allow the cake to cool in the pan for 8 to 10 minutes, then run a knife down the sides of the cake to ensure it's loose. Invert the cake onto a wire rack and let it cool for at least 30 minutes.
To make the chocolate ganache, place the chocolate in a medium heatproof mixing bowl.
Heat the heavy cream in a small saucepan on the stove until it's just simmering. Pour the hot cream over the chocolate, ensuring that the chocolate is submerged if necessary.
Let the mixture rest for about 4 minutes, then stir until the chocolate is melted and the mixture is smooth.
Pour the chocolate ganache over the cake. Allow it to cool slightly.
Cut the cake into slices and serve. Enjoy your homemade Chocolate Bundt Cake!