Sift the flour, cocoa powder, baking soda, cornstarch and salt together.
In another bowl, cream together the butter and both sugars until the sugar is starting to dissolve, about 5 minutes. Add the egg and egg yolk and continue beating until light in color. Stir in the coffee.
Add the wet ingredients to the dry ingredients and mix until combined. Fold in the chocolate chips and the chopped hazelnuts. Wrap the cookie dough in plastic foil and refrigerate for at least two hours and up to three days.
When ready to bake preheat the oven to 325°F. Line a few baking trays with parchment paper.
Allow the cookie dough to soften for 5-10 minutes before shaping it into balls of about 2-3 tablespoons dough each. This is easiest done with an ice cream scoop.
Lay the dough balls on baking sheets with enough space in between as they will spread. You can fit about 8-10 cookies on a baking tray.
Bake for 10-12 minutes. remove from the oven and let rest on the baking tray for another 10 minutes before cooling completely on a wire rack.
Store in an airtight container for up to a week.
Serving: 1cookie | Calories: 190kcal
Recipe created with ♡ for you by savorynothings.com