Coat a 9 by 5 loaf pan with vegan butter or cooking oil and line a parchment paper. Keep it aside.
Pre-heat oven to 350F.
In a bowl, add cooking oil, oat milk, apple cider vinegar, sugar and mix with a hand whisk.
In a seperate bowl sieve flour, baking soda, baking powder, salt and mix together. Now add dry ingredients to wet and fold in.
Divide plain batter equally into two separate bowls. Add vanilla extract to one batter bowl and mix well to get Vanilla batter. Add cacao powder and coffee powder to another bowl and mix well to get Chocolate batter.
Now scoop each of the Vanilla batter and Chocolate batter into the prepared loaf pan as shown in the images above. Continue till both batters are complete.
To create a marbling effect, run a skewer or end of a spoon through the batter in swirling motion. Do not overdo it, just move through the batter once.
Tap the loaf pan lightly on the countertop once to remove any air bubbles.
Bake for 45 - 50 mins or till a toothpick inserted in the center of the cake comes out clean.
Let the cake cool completely before slicing!
STORAGE: Can wrap in a cling wrap and store at room temperature for up to 3 days.