Preheat your oven to 350 degrees and generously grease a loaf pan with baking spray. Optionally line the pan with parchment paper for easy removal. I’m using an 8×4 inch loaf pan, but you can use a larger one as well, it just may take less time to bake.
In a medium bowl, stir together the flour, baking powder, and salt, and set the mixture aside. In a large bowl, beat together the butter, oil, and sugar until smooth and fluffy, about 1-2 minutes. Add in the sour cream, vanilla extract, and one egg- stir until well combined. Then, beat in the second egg.
Add in about 1/3 of the flour mixture and stir until well combined. Then add in about half of the buttermilk and stir to combine. Repeat until all of the buttermilk and flour mixture has been added. The batter should be very thick.
For the carrot cake swirl
Scoop about 1/3 of the main batter into another medium bowl. Add in the flour, shredded carrot, cinnamon, ground ginger, and cloves and stir until everything is well combined.
Begin scooping your two cake batters into your cake pan in alternating additions- you can use a scoop or just a spoon to put dollops of each batter into your pan. Then use a knife or a long toothpick to swirl the cake batters together, being sure to bring the knife all the way to the bottom of the pan.
Bake the cake for 55-60 minutes, until a cake tester comes out clean. Cool completely in the pan and then remove to slide and serve!