In a saucepan, melt butter on medium heat.
Once butter is added, add milk powder. Whisk constantly until golden brown.
Turn off heat and add granulated sugar and brown sugar.
Transfer the mixture to a large bowl. Add ice cube and stir in.
Add egg and vanilla and whisk until smooth.
Add flour, espresso, baking soda and salt. Fold with a spatula until just combined.
Fold in chocolate until just combined. Cover with plastic wrap and chill for at least 4 hours.
Preheat oven to 375℉ and line a cookie sheet with parchment paper. Let the dough come to room temperature for 1 hour, then scoop in 1/4 cup cookie balls.
Bake for 10-13 minutes until the center of the cookies no longer look wet.