Preheat the oven to 350 degrees.

Spray a 9×9" metal pan with non-stick spray. Set aside.

Melt the semi-sweet chocolate chips and salted butter together. Set aside to cool slightly.

Sift the flour, cocoa powder, espresso powder, and salt together in a small bowl. Set aside.

In a large bowl, add the eggs, granulated white sugar, and vanilla. Mix with an electric mixer for three minutes until the mixture is pale in color.

Add the melted chocolate and butter to the sugar/egg mixture. Gently fold in the chocolate until combined.

Add the dry ingredients and gently fold them in just until everything is combined together.

Pour the batter into the prepared pan.

Bake the brownies for 34-40 minutes, just until the center only wobbles slightly when the pan is shaken.

Let the brownies cool completely for at least three hours before cutting into them. Once cool, remove the brownies from the pan and cut into 16 squares.