Cream the butter and sugars

• Add 1 cup of cold butter to the bowl.
• Add the white sugar and the brown sugar.
• Cream everything together for 9 to 10 minutes until very light and fluffy — this is the foundation of the cookie.

Add baking soda, salt and eggs

• Add the baking soda and the salt to the creamed mixture.
• Add the eggs one at a time, mixing well after each addition.
• Scrape down the sides of the bowl and mix everything in.

Add the flours

• Add a little of the cake flour and a little of the plain flour.
• Mix until just combined — the dough will be very light, almost like cake batter.

Fold in chocolate and walnuts

• Add the dark chocolate and the milk chocolate.
• Add the 2 cups of chopped walnuts.
• Mix briefly until the chocolate and walnuts are evenly distributed.

Scoop the cookies

• Use an ice cream scoop to portion the dough into very large balls.
• Place only 4 cookies per baking tray, as they spread a lot.

Bake

• Bake for 9 to 12 minutes until the edges are set and the centers still look soft.
• Let the cookies cool slightly before serving — they melt in your mouth.