Preheat your oven to 350°F. Grease your Bundt pan thoroughly and set aside.
In a large bowl, combine the boxed cake mix with the sour cream, whole milk, vegetable oil, and vanilla extract. Using a hand mixer or an electric mixer fitted with the paddle attachment, blend the ingredients until combined. The batter should be smooth and slightly thick.
1 box (15.25 oz) cake mix, ¾ cup sour cream, ¾ cup whole milk, ½ cup vegetable or canola oil, ½ teaspoon vanilla extract
Pour the batter into your prepared Bundt pan. Use a spatula to spread the batter evenly and smooth the top. Bake for 45-50 minutes, or until a toothpick inserted into the center of the cake comes out clean. Allow the cake to cool in the pan completely before inverting onto a plate.
Notes
Any standard sized boxed cake mix should work, but I like to use gluten free cake mix.
Use full-fat sour cream and whole milk for best results.
It's crucial to let the cake cool completely before attempting to remove it from the pan, otherwise it may break or stick.