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.