Preheat your oven to 410°F. Yep, it's a bit high, but that’s how you get those crispy outsides and gooey middles.
In a large bowl or stand mixer, beat the cold butter and both sugars until light and fluffy—about 4 minutes.
Add eggs one at a time, mixing well after each. Try not to eat the dough yet. I know it’s tempting.
Whisk together cake flour, all-purpose flour, cornstarch, baking soda, and salt in a separate bowl.
Gradually mix the dry ingredients into the wet. The dough will be thick—arm day, anyone?
Fold in the chocolate chips (and walnuts, if you're into that).
Scoop big mounds—like, really big—about 6 oz each. Chill for 10 minutes if your kitchen’s warm.
Bake 9–11 minutes. The edges should be golden, the tops slightly cracked, and the centers just underdone.
Let cool on the sheet for 10 minutes before transferring. Or don’t. I won’t judge.