01 -
In a stainless steel pan, cook the butter on medium heat until the milk solids turn a deep amber color (around 10 minutes). Pour butter and solids into a mixing bowl.
02 -
Stir in the espresso grounds and allow the butter mixture to cool to room temperature (about 20-30 minutes).
03 -
Whisk together the cooled butter mixture with both sugars until fully blended (about one minute).
04 -
Whisk in the egg, yolk, and vanilla until the mixture is smooth.
05 -
Gradually fold in the flour, baking soda, salt, and chocolate until the dough just comes together.
06 -
Place dough balls on a tray lined with parchment paper and freeze them for at least 3-4 hours, or ideally overnight.
07 -
Preheat the oven to 350°F (180°C). Bake cookies placed 2 inches apart for 10-12 minutes, until the edges are golden and the centers look puffy and pale.
08 -
Transfer the baked cookies to wire racks to cool completely while keeping them on the baking sheet.