Place 2 sticks unsalted butter in the bowl of a stand mixer fitted with the paddle attachment and and let sit until softened. (Alternatively, use a large bowl and electric hand mixer.) Add 3/4 cup granulated sugar and 3/4 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 1/3 cups all-purpose flour in increments, mixing until just combined.

Add 2 cups chocolate chunks and 3/4 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.