Preheat oven to 350 degrees. In a medium sized bowl combine melted butter and sugar and whisk for 1 minute. Next, add in the vanilla extract and egg and whisk for another 1-2 minutes. I used a hand whisk, but you could also use and electric mixer.
Add in remaining ingredients and stir until just combined. Do not over stir the batter, this will help give the brownie a fudgey texture. Once combined add to a buttered 5-6 inch iron skillet, top with extra chocolate chips if desired.
Bake on the center rack for 20 minutes or until a toothpick comes out mostly clean. Serve warm and top with optional toppings if desired. Enjoy!