01 -
Warm butter in a steel pan over medium heat until it turns golden brown and smells nutty (around 10 minutes). Pour the butter and all bits into a mixing bowl.
02 -
Add ground espresso to the butter and let it cool completely to room temperature, which may take about 20-30 minutes.
03 -
Stir both sugars into the butter mixture for roughly one minute until it’s all perfectly mixed together.
04 -
Mix in the egg, yolk, plus vanilla and whisk until the batter looks smooth and creamy.
05 -
Carefully add in flour, baking soda, salt, and chocolate—don’t overmix; just stir until it all comes together.
06 -
Scoop dough onto a tray lined with parchment paper. Freeze for a minimum of 3-4 hours; best results when left overnight.
07 -
Heat oven to 350°F (or 180°C). Place the frozen dough balls 2 inches apart on the tray and bake 10-12 minutes, until edges are golden but centers look soft.
08 -
Cool cookies on a tray set over a wire rack to stop them from overbaking.