Preheat oven to 325 degrees. Line square glass baking pan with parchment paper.
In 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.
It is so important to sift your dry ingredients, as cocoa powder can form lumps in your batter that will not taste good in the final product.
Be sure to use cocoa powder that is JUST cocoa powder and check the date for expiration.
Be sure to use UNSALTED butter, not salted butter.
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.
It is NOT necessary to use parchment paper to bake these brownies. You can simply grease the pan instead.
A glass baking dish works best to bake brownies, but in a pinch use an stainless steel pan.
Store brownies in an airtight container at room temperature for 3-4 days.