Step 1

Preheat the oven to 350 degrees F. Spray an 8-inch baking dish with nonstick spray, then line it with a strip of parchment paper (edges hanging over), and spray the parchment with nonstick spray too.

Step 2

In a medium bowl, whisk together the flour, baking powder and salt. In a large, microwave-safe bowl, heat the butter and chocolate until butter is melted (about 75 seconds). Whisk the butter and chocolate together until the chocolate is melted and smooth (heat a few more seconds, if needed). Alternately, you may melt the butter and chocolate together in a pan set on top of a pot of simmering water. Remove from heat. Whisk the sugars into the mixture. Then whisk in the eggs, yolk and vanilla. Stir in the flour mixture until well incorporated. Fold in the chocolate chips.

Step 3

Pour the batter into the prepared pan and bake for 25 to 30 minutes. Bake until a skewer inserted into the center of the brownie comes out clean. Remove from the oven and cool completely before adding the glaze.

Step 4

In a small bowl, combine the powdered sugar, cocoa and vanilla. Whisk in 4 teaspoons of hot water, then add more water- 1 teaspoon at a time- until you reach a desired glaze consistency. You want to be able to pour it on the brownies.

Step 5

Use the parchment paper to move the brownies from the pan to a cutting board. Pour the glaze on top of the brownies, and use the bottom of a spoon to gently spread it to the edges. Let the glaze set (chill if you'd like) before cutting.