Preheat the oven to 325°F and spray an 8×8-inch metal baking pan with nonstick cooking spray or line it with parchment paper. Set aside.

Place the butter in a large bowl and cover the bowl with paper towels. Microwave until the butter is melted and very hot.

Add the sugar to the melted butter and whisk for about 2 minutes. Add the eggs and continue to whisk for another minute.

Add the salt, cocoa powder, and flour to the mixture. Stir until just combined.

Add the chocolate chips and vanilla and stir until just combined.

Spread the batter into the prepared pan and bake on the center rack of the oven for 25 to 30 minutes or until the center of the brownies is just set.

Cool before slicing and serving. Store leftovers at room temperature in an airtight container.