Levain-style chocolate chip cookies

Cut a cup of refrigerator cold butter into small cubes.

Cream it in a stand mixer with 400 g white sugar, very slowly at first so it does not warm up, then beat until creamy and smooth with no chunks of butter.

Add two cold eggs one at a time, then two teaspoons of vanilla paste.

Add a mixture of 180 g all-purpose flour, 173 g cake flour, two teaspoons of kosher salt and one and a half teaspoons of cornstarch, scraping down the bowl.

Mix in a cup of semi-sweet chocolate, a cup of dark chocolate and a cup and a half of walnuts.

Measure out 170 gram chunks, cover and refrigerate one hour.

Bake at 400 degrees Fahrenheit for about 10 minutes; the point is not to cook them through, they stay dough on the inside with a browned exterior.

Variation: a slightly lower temperature, 375 to 380 on convection, browns them more evenly and gives more browning on top.