Prep your pan and oven. Heat the oven to 350°F (175°C). Lightly grease a 24-cup mini muffin pan or line with mini paper liners.
This helps the bites release cleanly.
Whisk the dry ingredients. In a medium bowl, whisk flour, cocoa powder, baking powder, and salt until evenly combined. Breaking up cocoa clumps now keeps the batter smooth later.
Mix the wet ingredients. In a separate bowl, whisk the granulated sugar, brown sugar, egg, oil, Greek yogurt, and vanilla until glossy and well combined.
Bloom the cocoa. Pour the hot coffee (or water) into the wet mixture and whisk. The heat helps intensify the cocoa flavor for a richer brownie bite.
Combine gently. Add the dry ingredients to the wet and stir with a spatula just until no streaks remain.
Fold in the mini chocolate chips. Do not overmix—this keeps the texture fudgy.
Portion the batter. Use a small cookie scoop or spoon to fill each mini muffin cup about 3/4 full. Aim for even portions for consistent baking and calories.
Bake. Bake for 9–11 minutes, until the tops are set and a toothpick inserted in the center comes out with a few moist crumbs (not wet batter).
Slightly underbaked is better than overbaked here.
Cool. Let the bites cool in the pan for 5 minutes, then loosen edges with a thin knife and transfer to a rack to cool completely. They firm up as they cool.