You can bake these right away as I do, or refrigerate up to 36 hours, freeze for up to 3 months. If baking same day, preheat oven to 350 °F
In a medium bowl whisk the flours, corn starch, baking soda, baking powder, and salt.
With the paddle attachment of your stand mixer cream butter and sugars on medium-high until fluffy and light colored, this takes about 5 minutes. I stop it at least once, usually twice to scrape during that 5 minutes.
Add room temperature eggs, one at a time, incorporating well after each.
Stir in the vanilla, scrape down the batter, ensuring everything is well blended.
With the mixer on low, add the dry ingredients, after 20 seconds add chocolate chips/chunks, and walnuts, do this before the flour is entirely incorporated, do not overmix. Often after 20-30 seconds I will hand mix using a wooden spoon, the dough is very thick and on the dryer side.
Scoop 3 1/2 ounces of dough onto parchment lined cookie sheet, rounding gently, do not overly compress, sprinkle with sea salt. Only 6 to a sheet, these are large cookies. If you choose to chill, you would do so at this point. Covered in the refrigerator for 60 minutes up to 36 hours.
In a preheated 350 °F oven bake for 18-20 minutes or until lightly golden brown, if they are still quite rounded, take a spatula and gently press down to flatten, cool on cookie sheet for 3 minutes before moving to cooling rack.