Preheat your oven to 180°C (350°F). Line the 8x8 inch baking pan with parchment paper, leaving an overhang on the sides for easy removal.

Melt the butter in a medium saucepan over low heat. Remove from heat and stir in both granulated sugar and brown sugar until fully combined.

Let the mixture cool for 2 minutes. Add the eggs, one at a time, whisking vigorously after each addition. Stir in vanilla extract.

In a separate bowl, sift together flour, cocoa powder, salt, and baking powder.

Add the dry ingredients to the wet ingredients. Using a rubber spatula, fold the batter together until there are no streaks of flour.

Gently fold in the dark chocolate chips or chunks.

Pour the batter into the prepared baking pan. Smooth the top evenly with a spatula.

Bake in the preheated oven for 25 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs (not wet batter).

Remove from the oven and cool the brownies in the pan on a wire rack for at least 20 minutes. Use the parchment overhang to lift the brownies out of the pan and cut into 12 squares.