Preheat oven to 350˚F and lightly coat a 24-cup mini muffin pan with cooking spray.
In a medium-sized microwave-safe bowl, place the butter and chocolate chips, then microwave for approximately 1 minute until melted. Alternatively, you can use a bowl over simmering water, stirring until the melted mixture is smooth and well combined.
Add sugar and cocoa powder to the melted mixture, whisking until fully combined. Whisk in the eggs, one at a time, and stir in the vanilla until combined.
Add flour and salt and use a rubber spatula to fold together until no flour streaks remain.
Using a medium spring-loaded cookie scoop, scoop about 1.5 tablespoons of the batter evenly into the muffin pan. Bake for 12 minutes or until the brownies are set on the sides, being careful not to over bake. Remember, the brownies will continue to set as they cool in the pan.
Once baked, transfer the pan to a wire rack and allow the brownies to cool completely, about 30-45 minutes, before removing them from the pan.