Preheat oven to 350°F. Grease an 8 by 8-inch baking dish or pan and set aside.
Melt the butter in a large, microwave-safe bowl. Use a whisk to stir in the brown sugar until well-combined. Beat in the egg and vanilla until completely incorporated. Blend in the flour and salt until fully blended. Fold in half of the chocolate chips.
Scrape the batter into the prepared dish or pan, smooth the top, and sprinkle with the remaining chocolate chips. Bake for 20 to 25 minutes or until center is set. Set the pan on a wire rack to cool before slicing.