Preheat oven to 325 degrees. Line square glass baking pan with parchment paper.
In a small saucepan, melt butter over low heat. Add in espresso powder and sugar and whisk to combine. Cook over low heat for 2-3 minutes, until sugar begins to melt into butter, whisking often. Remove from stove and cool while sifting dry ingredients.
Sift flour, cocoa powder, salt, and baking powder into a large mixing bowl. Add in chocolate chips and toss to coat.
Add butter mixture, vanilla, and eggs to dry ingredients. Mix together with wooden spoon or spatula until JUST combined. Do NOT overmix or brownies will become tough.
Pour brownie batter into pan and spread gently for brownie batter to be evenly distributed in pan.
Bake brownies for 30-35 minutes, or until the center is set, but still soft. A toothpick should come out clean with a few crumbs still attached.
Sifting: It is so important to sift your dry ingredients, as the cocoa powder can form lumps in your batter that will not taste good in the final product.Cocoa Powder: Be sure to use a cocoa powder that is JUST plain cocoa powder and check the date for expiration.Espresso Powder: The added instant espresso powder helps to really make the chocolate flavor stand out. Feel free to omit or use decaffeinated espresso powder as well.Parchment Paper: It is NOT necessary to use parchment paper to bake these brownies. You can simply grease the pan instead. Baking Dish: A glass baking dish works best to evenly bake brownies, but in a pinch use a stainless steel pan.Storage: Store cooled brownies in an airtight container at room temperature for 3-4 days or freeze brownies individually wrapped in an air-tight container for up to 3 months. Chocolate Chips: Use semi-sweet, dark, or milk chocolate chips in the brownie batter. You can also use a good-quality bar of chocolate you enjoy eating plain in place of the chocolate chips, simply chop the bar up into small morsels before adding to the batter. Nuts: If desired, add ½ cup chopped pecans or walnuts to the batter when adding the chocolate chips to the flour mixture.