• Begin by preheating your oven to 350°F. Grease and flour a 10-12 cup bundt cake pan.
• In a medium-sized mixing bowl, whisk together the flour, baking powder, baking soda, salt, and instant vanilla pudding mix. Set aside.
• In a large mixing bowl, use a mixer on medium speed to cream together the butter, oil, and sugar until light and fluffy.
• Add the eggs one at a time, beating well after each addition.
• Stir in the vanilla extract.
• Add the dry ingredients to the wet ingredients in three parts, alternating with the sour cream and whole milk, starting and ending with the dry ingredients. Mix until just combined.
• Divide the batter into two separate bowls. Add the melted chocolate to one of the bowls and stir until combined. If the batter becomes too thick, thin it with milk so that both batters are of equal consistency.

Making the Stripes

• Transfer each batter to a separate piping bag. Cut the tip of the bags so each has a 1/2-inch wide opening. Pipe a circle of one batter into the bundt pan, then flatten it down with a spoon or rubber spatula.
• Pipe a circle of the other batter on top of the first circle. Repeat until the pan is full.
• Tap the pan on the counter a few times to remove any air pockets and help the batter spread evenly.
• Bake the cake for 50-55 minutes, or until a toothpick inserted into the center comes out clean. Allow the cake to cool in the pan for 10 minutes, then turn it out onto a wire rack to cool completely.

Making the Glaze

• To make the chocolate glaze, heat the heavy cream in a small saucepan on low heat until it just begins to simmer. Remove from heat and pour the chocolate chips into the pan.
• Let sit for a minute, then whisk until smooth.
• Pour the glaze into a glass measuring cup with a pour spout or small creamer.
• Drizzle the chocolate glaze over the cooled cake, allowing it to drip down the sides.
• Serve and enjoy!