Pre-heat oven to 350 degrees. Grease 9x13 baking pan.
In a large, microwave safe bowl, melt together the butter and chocolate chips. In my microwave, this took approximately 1 minute. Stir together the butter and chocolate chips.
Add in the 2 cups granulated sugar and stir to combine.
Crack in the 3 eggs and stir to combine.
Add in 1 teaspoon baking powder and stir to combine.
(Gently) dump in the 1 cup all-purpose flour and stir to combine.
Pour batter into grease 9x13 baking pan and put in the oven for approximately 25 minutes. Top should not be glossy and toothpick should come out clean.