Preheat your oven to 350°F and line an 8x8-inch baking pan with parchment paper. Grab a large bowl and whisk together the flour, baking powder, cocoa powder, and salt. Set this dry mixture aside for now—we'll need it in just a second.

In another bowl, cream together the butter and sugar until it looks light and fluffy, about 2-3 minutes. Beat in the 3 eggs one at a time, then add the vanilla extract and mix until everything's combined. Don't worry if it looks a little thick at this point.

Fold the dry ingredients into your wet mixture until you don't see any white streaks of flour anymore. Stir in the chocolate chips gently—you want them distributed throughout but not crushed up. The batter should look thick and chocolatey at this stage.

Pour the batter into your prepared pan and spread it evenly. Bake for 25-28 minutes until a toothpick inserted in the center comes out with just a few moist crumbs. Don't overbake or they'll get cake-like instead of fudgy—I learned that the hard way.

While those bake, make your mint frosting layer. Finely chop the fresh mint leaves and set aside. In a small bowl, beat together the powdered sugar, heavy cream, and mint until you get a smooth, spreadable consistency.

Pull the brownies out and let them cool for about 10 minutes—they need to be warm enough that the frosting spreads easily but cool enough that it doesn't melt. Spread that gorgeous mint frosting all over the top of the warm brownies.

Stick the pan in the fridge for at least 2 hours so the frosting sets completely. Once it's firm, cut into 16 squares and serve them up. They'll keep in an airtight container for up to 5 days, though honestly they never last that long around here.