Pre-heat oven at 350°F (180°C).

In a medium bowl sift the flour, baking powder and salt. Set aside.

In a large bowl beat the butter, oil and sugar until it’s all soft and creamy. Now add one egg at a time and add the vanilla extract along with the last egg.

Add the flour mixture in 3 batches alternating with the amount of milk, which will be added in 2 batches. Begin and end with the flour mixture. Mix only until each ingredient is incorporated without over mixing, otherwise, you will end up with a tough cake. Make sure to scrape the bowl well to make sure everything has been incorporated.

Divide the batter into two separate bowls however you want. If you want it to be half vanilla and half chocolate, divide it into equal parts. If you want it to be more vanilla than chocolate then pour about 1/3 of batter into a separate bowl to make it into chocolate, etc.. Add the cocoa powder into the batter that will be the chocolate cake and stir until it is incorporated.

Pour each batter into a prepared large Bundt pan alternating between each flavor. I use a spoon to make a thin layer of each. Then, with a chopstick, wooden skewer or knife gently swirl the batter to get that marble look. Bake for about 35-40 minutes or until a toothpick or knife inserted in the center comes out clean.

Take the cake out of the oven and let it rest on a cooling rack for about 10 minutes. Then take it out of the pan and let it cool completely.