Preheat the oven to 350°F/180°C. Line a square 8×8 baking pan with parchment paper and set it aside.
Brown the butter: Melt the butter in a medium sized pan over medium heat. Once it melts, it will crackle, then become foamy – continue mixing the butter while this happens to prevent burning. The butter will go from melted to golden brown quickly, and you'll know it's almost done when the aroma of browned butter arrives. The whole process should take about 5 minutes! Once golden, remove from heat and transfer to a glass bowl.
3/4 cups unsalted butter
In a large bowl, mix together the browned butter and light brown sugar. You may use a whisk or spatula.
1 1/2 cups light brown sugar
Add in the eggs and vanilla and continue whisking.
3 eggs, 1 tbsp vanilla
Add in the cocoa powder, flour, and salt. Using a spatula, gently fold in the dry ingredients until a soft brownie batter forms.
3/4 cups cocoa powder, 3/4 cups all-purpose flour, 1/2 tsp salt
Toss in the chocolate chunks and mix in a few times. Don't over-mix!
1/2 cup chocolate chunks
Transfer into prepared baking pan. Bake for 25-30 minutes. The top will no longer look shiny, and the edges will be set. A toothpick inserted should come out with moist crumbs, not wet like batter. If it's wet, they're not ready, so bake for an additional 5 minutes.
Allow the brownies to cool before slicing. If you slice them while they're warm, they will fall apart. Sprinkle some sea salt if you'd like, slice, and enjoy!
flakey sea salt