In the bowl of your stand mixer or a large mixing bowl, cream together the sugars - both white and brown and the butter cubes, until really creamy

Add in one egg, mix until well incorporated, then add the other egg and mix well again

Stir in the flour, baking powder, salt. Mix until combined.

Add in the chocolate chips and chopped walnuts

Using a very large scoop, divide the dough into 10 equal portions on a cookie tray and cover with a cling wrap

Chill in the freezer for at least an hour

Preheat the oven to 375*F

Spread out the scooped out cookie dough on two baking sheets , 5 on each sheet , leaving some space between them as the cookies will spread out when baking

Bake cookies for 18 minutes, or until tops are browned

Wait a couple of minutes before carefully lifting each cookie onto a wire rack to cool for at least 15 minutes. Because the cookies are thick, they need extra time to firm up