Nonstick cooking spray
8 large eggs
Kosher salt and freshly ground black pepper
2 cups loosely packed baby spinach leaves, roughly chopped
1 small red, yellow or orange bell pepper, finely chopped (about 3/4 cup)
2 scallions, finely chopped
2 tablespoons chopped fresh basil
2 tablespoons chopped fresh Italian parsley
1 cup grated Havarti (about 4 ounces)
1/4 cup grated Parmesan
Spray an 8-inch round nonstick cake pan with cooking spray. Whisk the eggs in a large bowl with 1 teaspoon salt and several grinds of pepper. Add the spinach, pepper, scallions, basil and parsley and stir to combine. Fold in the Havarti and Parmesan.
Preheat a 3.5-quart air fryer to 310 degrees F. Pour the mixture into the prepared cake pan and place in the basket. Cook until the frittata is slightly puffed, deep golden and a tester inserted in the center comes out clean, about 25 minutes.
Let the frittata cool in the pan for 10 minutes before unmolding. To unmold, invert onto a plate, then invert again, browned-side up, onto a serving plate.