- Preheat the oven to 350°F and grease a mini muffin pan. 
- In a bowl, combine cake mix, eggs, sour cream, milk, oil, and vanilla. Mix until smooth. 
- Scoop the batter into the muffin cups, filling each about 2/3 full. 
- Bake for 10–12 minutes or until a toothpick comes out clean. Let them cool slightly in the pan. 
- While the bites bake, melt butter in a saucepan over medium heat. Add cocoa and milk, stir until smooth. 
- Remove from heat, then whisk in powdered sugar and vanilla until glossy. 
- Drizzle the warm glaze over the slightly cooled cake bites or dip the tops directly into the glaze. 
- Let the glaze set before serving, or don't—it’s your kitchen.