Creating these brownie bites is a straightforward process. Follow these steps to make your batch of deliciousness:

1. Preheat Oven: Start by preheating your oven to 350°F (175°C). Grease a mini muffin pan or line it with paper liners.
2. Melt Butter: In a medium saucepan over low heat, melt the butter. Stir occasionally until completely melted.
3. Mix Sugars: Remove the saucepan from heat and mix in both granulated and brown sugars until well combined.
4. Add Eggs: Allow the mixture to cool briefly, then whisk in the eggs, one at a time, followed by the vanilla extract.
5. Combine Dry Ingredients: In a separate bowl, sift together the flour, cocoa powder, baking powder, and salt.
6. Combine Mixtures: Gradually fold the dry ingredients into the wet mixture until just combined. Do not overmix.
7. Add Chocolate Chips/Nuts: If using, gently fold in chocolate chips and chopped nuts for added flavor and texture.
8. Fill Muffin Pan: Spoon the batter into each muffin cup, filling them about two-thirds full.
9. Bake: Place the filled muffin pan in the preheated oven and bake for 15-20 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
10. Cool: Remove from the oven and allow to cool in the pan for about 10 minutes before transferring the brownie bites to a wire rack to cool completely.

These simple steps will lead you to a batch of irresistible brownie bites!