01 -  Preheat oven to 350°F. Lightly grease a 24-cup mini muffin pan or line with mini paper liners. 
 02 -  In a small saucepan, melt the butter over low heat. Remove from heat and stir in sugar until well combined. Allow mixture to cool slightly. 
 03 -  Whisk in eggs one at a time until fully blended. Add vanilla extract and stir until smooth. 
 04 -  In a separate bowl, sift together flour, cocoa powder, baking powder, and salt. 
 05 -  Gradually stir dry ingredients into wet mixture until just combined. Fold in chocolate chips. 
 06 -  Divide batter evenly among mini muffin cups, filling each about three-quarters full. 
 07 -  Bake for 12 to 15 minutes, or until a toothpick inserted in the center emerges with moist crumbs. 
 08 -  Let brownie bites cool in pan for 5 minutes, then transfer to a wire rack to cool completely.