Step 1: Prepare Pan & Oven

• Preheat oven to 350°F (175°C).
• Grease and flour a Bundt pan thoroughly.

Step 2: Make Cake Batter

1. In a bowl, whisk together flour, baking powder, baking soda, and salt.
2. In a large bowl, cream together butter and sugar until light and fluffy.
3. Beat in the eggs one at a time, then add vanilla, sour cream, and buttermilk.
4. Gradually add in the dry ingredients and mix until smooth.

Step 3: Make Chocolate Batter

1. In a separate bowl, mix cocoa powder and hot water into a paste.
2. Stir about ⅓ of the vanilla batter into the cocoa mixture to make the chocolate portion.

Step 4: Make Cream Cheese Swirl (Optional)

1. Beat together cream cheese, sugar, egg yolk, and vanilla until smooth.

Step 5: Swirl & Bake

1. Pour half the vanilla batter into the pan.
2. Spoon in the chocolate batter and cream cheese filling in alternating dollops.
3. Pour the remaining vanilla batter on top.
4. Use a knife or skewer to swirl the batters together in a tornado pattern.
5. Bake for 50–60 minutes, or until a toothpick comes out clean.
6. Let cool for 15–20 minutes in the pan, then invert onto a rack to cool completely.

Step 6: Glaze & Serve

1. Whisk glaze ingredients until smooth.
2. Drizzle over cooled cake in swooping motions for that swirling effect.