• Preheat the oven to 350 degrees Fahrenheit (175 degrees Celsius). Butter and flour a large 10-15 cup Bundt pan, and set aside.
• In the bowl of a stand mixer or a large mixing bowl with a hand mixer, beat butter until creamy, about 1 minute. Add sugar and beat on medium speed for 3 minutes or until pale. Add eggs one at a time, mixing after each addition. Add vanilla extract and mix until combined.
• In a medium mixing bowl, whisk together the flour, baking powder, baking soda, and salt. With the mixer on low, alternate adding the dry ingredients with the milk and sour cream. Mix until just combined.
• Remove 2 1/2 cups of batter and place in a small mixing bowl. In a small bowl, whisk together cocoa powder, oil, water, and optional espresso powder. Gently fold into the reserved batter until no streaks remain.
• Using a standard-sized cookie scoop or spoon, alternate adding yellow and chocolate batter to the pan. After the bottom of the pan is no longer visible, gently swirl the batter (be careful not to overdo it). Repeat with two additional layers. Tap the pan on the counter to even the batter out.
• Place in the oven and bake for 45-55 minutes or until a cake tester inserted into the center comes out clean or the cake springs back when touched.
• Remove from the oven and allow to cool for 15 minutes in the pan before inverting onto a wire rack to cool completely. Once cool, dust with powdered sugar if desired.

Chocolate Fudge Ganache

• In a medium-sized glass mixing bowl, combine 1 cup of semi-sweet chocolate chips, 1/2 cup of milk chocolate chips, and 2/3 cup of heavy cream.
• Place the bowl in the microwave and heat on half power for 1 minute. Stir, then repeat once more.
• Stir until all of the chocolate chips are melted and smooth. Beat vigorously for 1 minute. Pour over the Bundt cake when it reaches your desired consistency. If you want a thicker glaze, let it sit for at least 5 minutes before pouring. Allow to set for 30 minutes before cutting.