01 - Preheat the oven to 350°F. Grease a 24-cup mini muffin pan or line it with mini paper liners.
02 - In a medium bowl, whisk together the flour, cocoa powder, baking powder, and salt until evenly blended.
03 - In a large bowl, whisk melted butter and sugar until fully combined. Add eggs and vanilla extract, whisking until smooth.
04 - Gradually fold the dry ingredients into the wet mixture, mixing gently until just combined to avoid overmixing.
05 - Stir in semi-sweet chocolate chips and nuts if using, ensuring even distribution throughout the batter.
06 - Divide the batter evenly among the 24 mini muffin cups, filling each approximately three-quarters full.
07 - Bake for 12 to 15 minutes until the tops are set and a toothpick inserted in the center comes out with moist crumbs.
08 - Allow the brownie bites to cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.