Preheat your oven to 350 degrees Fahrenheit, 175 degrees Celsius.

Grab an 8x4 or 9x5 loaf pan and line it with parchment paper, leaving some overhang on the sides for easy removal.

In a large mixing bowl, take 6 tablespoons of melted unsalted butter, 1/3 cup of granulated sugar, and 1/4 cup of brown sugar.

Then, crack 1 large egg at room temperature and ½ tsp of vanilla essence or extract into the mixing bowl.

Use a stand mixer or a hand mixer to beat them until well combined.

Sift in ¼ cup of all-purpose flour and add 1/4 cup of cocoa powder into the brownie batter.

Then, sprinkle 1/4 tsp of salt and 1/4 cup chocolate chunks into the batter.

Fold the ingredients with a spatula until just combined.

Pour the brownie batter into the parchment-lined pan and spread it evenly with a spatula.

Sprinkle some additional chocolate chips on top, if desired.(optional)

Bake the brownies in the preheated oven for 25-30 minutes or until the edges are set.

To check its doneness, insert a toothpick into the middle- it should come out clean or with a few crumbs.

Once baked, remove the brownie from the oven and let the brownie cool in the pan for at least 10 minutes before slicing.

Use the parchment to lift the brownie from the pan and cut into desired slices.

Garnish the brownies with flaky sea salt, and enjoy your homemade small batch of brownies!