Preheat oven to 400°F. Season chicken with salt and pepper.
Mix breadcrumbs, ¼ cup Parmesan, and Italian seasoning. Dip chicken in eggs, then coat with breadcrumb mix.
Heat oil in skillet over medium; brown chicken 2–3 minutes per side (don’t cook through).
Arrange browned breasts in a baking dish, spoon marinara over each, sprinkle remaining Parmesan and mozzarella.
Bake 15–20 minutes until cheese is bubbly and chicken reaches 165°F.
Meanwhile cook spaghetti per package; drain and toss with extra sauce.
Serve chicken over spaghetti, garnish with basil.