Preheat your oven to 350°F (175°C) and grease a 9x13 inch baking pan or line it with parchment paper.

In a medium saucepan, melt the butter over medium heat. Continue cooking, stirring frequently, until the butter turns a golden brown color and has a nutty aroma, about 5-7 minutes. Remove from heat and let cool slightly.

In a large mixing bowl, combine the granulated sugar and brown sugar. Pour the browned butter over the sugars and mix until well combined.

Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.

In a separate bowl, whisk together the flour, cocoa powder, espresso powder, and salt. Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Be careful not to overmix.

Fold in the chocolate chips until evenly distributed. Pour the batter into the prepared baking pan and spread it evenly.

Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs.

Allow the brownies to cool in the pan for at least 15 minutes before slicing into squares.