In a large mixing bowl, use a wooden spoon to mix the butter, sugars, and vanilla until well-combined. Add eggs one at a time, mixing after each addition.
Add half of the flour, all the baking soda, corn starch, and salt. Mix, then add the rest of the flour. You will think there is too much flour. There isn’t. Keep mixing. Once the flour is incorporated, mix the white chocolate, butterscotch, and nuts in.
Cover and chill for as long as you can bear it, at least 4 hours but preferably overnight. This is a very important step, so resist the urge to skip it entirely.
When ready to bake, preheat oven to 350 degrees F. Scoop dough into 2-tablespoon mounds and place onto an ungreased baking sheet. Be sure to leave space between the cookies. Bake for 13-16 minutes or until starting to turn golden brown. Remove from oven, press a few extra chips on top, sprinkle generously with sea salt, and cool on baking sheet for ten minutes before moving them to a wire rack. I recommend letting them set for half an hour before eating.
