Melt the butter and chocolate together in a saucepan over medium heat. Whisk continuously with a whisk or a fork until both the butter and chocolate have melted and come together in a smooth mixture.
Take the mixture off the heat and let cool for five minutes.
Add the vanilla extract, brown sugar, and eggs
Now add the vanilla extract and brown sugar to the saucepan. Whisk until combined.
Now add the eggs to the saucepan. Whisk until the eggs are completely combined. The mixture should be smooth, shiny, and thick. (Like chocolate pudding.)
Add the dry ingredients
Next add the flour, salt and baking powder to the saucepan. Stir the dry ingredients in until the flour is almost completely incorporated.
Now add in the mint chips, and stir until the the chips and the dry ingredients are just incorporated into the wet ingredients. Don’t overmix.
Bake the brownies
Preheat the oven to 350 degrees, and oil an 8x8 inch glass baking dish.
Spread the brownie batter evenly into the baking dish. Smooth the top with an offset spatula.
Bake at 350 degrees for 30 minutes, until a toothpick inserted in the middle of the brownies comes out mostly clean.
Serve and enjoy
Let the brownies cool for 20 minutes before slicing. Serve and enjoy!