Step 1

Preheat oven to 350°F. Grease and line a loaf pan with parchment paper.

Step 2

In a large bowl, whisk together the flour, sugar, baking powder, and salt.

Step 3

In a medium bowl, whisk the eggs. Then, mix in the buttermilk, oil, and vanilla extract.

Step 4

Fold the wet ingredients into the dry ingredients just until the flour streaks are all gone. Then, transfer half of the batter into a separate bowl and gently stir the cocoa powder and hot water into it.

Step 5

Alternately spoon the vanilla and chocolate batters into the prepared loaf pan to create a marbled effect.

Step 6

Bake on the middle rack until a toothpick comes out of the center clean (about 55-70 minutes). Let it cool for 10-20 minutes, then lift it out of the pan and move it to a wire cooling rack.