Place 2 sticks unsalted butter in the bowl of a stand mixer fitted with the paddle attachment and let sit until softened. (Alternatively, use a large bowl and electric hand mixer.)
Add ¾ cup granulated sugar and ¾ cup packed dark brown sugar, and beat on medium speed until combined and fluffy, 3 to 4 minutes.
Add 1 tablespoon vanilla extract, 2 large eggs, and 1 teaspoon kosher salt, and beat until just combined.
Add 1 teaspoon baking soda and 2 ⅓ cups all-purpose flour in increments, mixing until just combined.
Add 2 cups chocolate chunks and ¾ cup chopped walnuts and stir with a rubber spatula until just combined.
Preheat an Instant Vortex Plus 7-in-1 Air Fryer Oven to BAKE at 350ºF and set to 5 minutes.
Line the air fryer racks with parchment paper, being sure to leave room on all sides for air to flow.
Drop 2-tablespoon scoops of the dough onto the racks, spacing them 1-inch apart.
Gently flatten each scoop slightly to make a cookie shape.
Sprinkle with flaky sea salt, if using.
Bake until golden brown, about 5 minutes.
Remove the racks from the air fryer and let cool for 3 to 5 minutes to set.
Repeat with the remaining dough.
Serve warm.
