INGREDIENTS
3/4 cup
unsalted butter (12 tablespoons), melted and slightly cooled
1 cup
brown sugar
1/2 cup
sugar
1
egg + 1 egg yolk
2 tsp
vanilla extract
1/2 tsp
baking soda
1/2 tsp
salt
1/2 tsp
espresso powder, optional (It just slightly enhances the chocolate flavor but is by no means necessary)
2 cups
+ 2 tablespoons all-purpose flour
2 cups
semisweet chocolate chips, divided