Start by browning your butter. In a pot over medium heat, melt the butter completely stirring frequently. The butter will go from very bubbly to have smaller bubbles and will start smelling nutty. Keep cooking until the butter starts taking a golden brown colour and you’ll see some brown pieces, once that has happened, take it off the heat and transfer to a glass bowl and let it come to room temp.
In a bowl, mix together the butter, brown and granulated sugar. Then, add it the egg and egg yolk and mix again.
Add in the vanilla extract and espresso grounds and mix again.
Finally fold in the flour and baking soda and mix until just combined.
Add the chocolate chunks and fold them in with a spatula.
Refrigerate your cookies in the fridge for at least 30 minutes, you can also keep them in the fridge overnight. The longer in the fridge, the deeper the flavour.
Cook in a preheated oven at 180 degrees celsius for 10-12 minutes until the edges start going brown and the centre still looks slightly undercooked.
