Preheat the oven to 325℉. Line an 8x8 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 the 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 a wooden spoon or spatula until JUST combined. Do NOT overmix or brownies will become tough.
Pour brownie batter into the prepared pan and spread gently for brownie batter to be evenly distributed in the 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.
Cool the brownies in the pan on a cooling rack for 10 minutes. Remove the parchment paper and let the brownies cool for an additional 10 minutes before slicing.
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Notes
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 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 instead of the chocolate chips, chop the bar up into small morsels before adding it 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.Dairy-Free Brownies: To make dairy-free brownies, use your favorite non-dairy stick butter, omit the added salt, and use dairy-free chocolate chips. While not quite as fudgy, they still turn out delicious.Gluten-Free Brownies: Use a 1:1 gluten-free all-purpose flour in place of the all-purpose flour.Eggless Brownies: For the best fudgy texture, use 1 tablespoon of aquafaba (liquid from canned chickpeas) in place of each large egg, rather than applesauce or flax eggs.