Marble Loaf Cake

Cream together the butter and sugar on high speed until light and fluffy.

Mix in the vegetable oil, heavy cream, and vanilla extract, continuing to beat until smooth and pale.

Add the eggs one at a time, beating for about 30 seconds after each addition.

Fold in the flour and baking powder until just combined.

Divide the batter in half. Stir cocoa powder and milk into one half until well blended.

Pour the batter into a well-greased loaf pan, alternating between the vanilla and chocolate portions to create the marble effect.

Give the pan a gentle tap on the counter to release any air bubbles before baking.