Preheat the oven to 350°F. Grease an 8×4 or 9×5 pan. For easy removal of the brownies, place parchment paper on the bottom and 2 sides of the pan. Grease on the sides and then set aside.
Melt the butter and while it's still hot, add in the chocolate chips and espresso and whisk it in. Allow to cool for at least 10 minutes while you prep the rest of your ingredients.
1/4 cup unsalted butter, 1/2 cup semi-sweet chocolate chips, 1/2 tsp espresso
Whisk in sugar until well combined. It may be grainy, but that is okay!
1/2 cup white sugar
Whisk in egg and vanilla for 1-2 minutes. Make sure to whisk for a good amount of time as this introduces air into the batter and allows for that shiny crackle top we all love on brownies.
1 egg, 1 tbsp vanilla
Using a spatula, gently fold in cocoa powder, flour, and salt until a soft brownie batter forms. Then mix in chocolate chips.
1/2 cup all-purpose flour, 1/2 tsp salt, 1/4 cup semi-sweet chocolate chips, 1/2 cup unsweetened cocoa powder
Pour into prepared pan and spread evenly. Top with extra chocolate chips if desired.
Bake for 20-25 minutes depending on your oven. Start checking after 20 minutes. The brownies will have set edges and the middle will look a little underbaked. When you insert a toothpick it'll come out with moist crumbs.
Sprinkle flakey sea salt (optional, but recommended) and enjoy!