Preheat oven to 425°F. Line a sheet pan with foil and spray the foil with olive oil spray.
Pat the 12 chicken tenders dry with paper towels and sprinkle them evenly with 1 teaspoon kosher salt.
Beat the 1 large egg in a shallow bowl.
Measure 1 cup seasoned breadcrumbs. Put 1/2 cup into a second shallow bowl for coating and set the remaining 1/2 cup aside in case you need extra for even coating.
One at a time, dip each chicken tender into the beaten egg, letting any excess drip off, then press into the 1/2 cup of breadcrumbs to coat both sides. Shake off excess breadcrumbs and place the coated tenders in a single layer on the prepared sheet pan.
Spray both sides of each coated tender generously with olive oil spray.
Bake the tenders on the sheet pan at 425°F for about 18 minutes, flipping once halfway through, until cooked through (internal temperature 165°F) and the coating is set.
Transfer the cooked tenders to a 9×13-inch baking pan in a single layer.
Spoon 1 1/2 cups marinara sauce evenly over the tenders.
Sprinkle 1 cup shredded part-skim mozzarella over the sauce, then sprinkle 1/4 cup grated Parmesan on top.
Bake in the 425°F oven for 8 to 10 minutes more, until the marinara is hot and the cheeses are melted.
Remove from the oven, garnish with chopped basil leaves, and serve immediately.