Preheat oven to 350 F.

Place butter, oil, and sugar in a large mixing bowl. Mix until smooth and combined. Add eggs, one at a time, and mix until thoroughly combined. Add red food dye, vanilla extract, and vinegar. Mix until combined.

In a medium bowl, sift together the flour, baking soda, kosher salt, and cocoa powder. Add to the red batter mixture in 3 batches, alternating with the buttermilk, starting and ending with flour. Mix well between each addition. Combine well after last flour addition, mixing for up to 2 minutes if necessary to remove all lumps.

Spray mini bundt pan with non-stick cooking spray. Fill the bundt pan 3/4 of the way to the top with the batter. Sprinkle 4-5 chocolate chips on top and bake for 15-18 minutes, until a toothpick inserted comes out clean. Let cool in the pan for 5 minutes and then invert onto a wire rack to cool completely before frosting.