Step 1

Preheat an oven to 180c (350f) and prepare a loaf pan with parchment paper.

Step 2

Into a big measuring cup or a small mixing bowl, add the buttermilk, vanilla extract, vegetable oil, sour cream, and mix with a whisk.

Step 3

Then into a medium mixing bowl, add the flour and baking powder. Mix with a whisk until combined.

Step 4

Into a big mixing bowl, add the soft butter, and sugar. Mix with an electric hand mixer until creamy and smooth for about 2 minutes.

Step 5

Add the room temperature eggs and mix until well combined.

Step 6

Then add 1/2 of the dry mixture and 1/2 of the wet mixture into the butter mixer and mix it until almost combined.

Step 7

Add the other half of the dry ingredients and the wet mixture until just combined.

Step 8

Divide the mixture in half sift the cocoa powder into one half of the cake mixture and mix until just combined. Don’t overmix.

Step 9

Scoop 1/4 cup of the vanilla mixture into the loaf pan, and 1/4 cup of the chocolate mixture. Repeat until you run out of cake batter. (as seen in the video)

Step 10

Use a toothpick or a butter knife to make swirls in the batter creating a marbled effect. Don’t overdo it so you don’t get a mixed batter.

Step 11

Bake in a 180c (350f) preheated oven for about 40-50 minutes or until a toothpick inserted into the cake comes out clean.

Step 12

Melt dark chocolate and heavy cream in a small to medium mixing bowl in the microwave for about 50 seconds.

Step 13

Let the chocolate and the cream sit for 10 minutes for the chocolate to melt, then mix until the chocolate ganache is smooth and silky.

Step 14

Place the chocolate ganache in the fridge for about 40 minutes or until it hardens and has a frosting-like texture.

Step 15

Frost the cake with the chocolate ganache and make a wave pattern with a spatula.