This is a good way to use leftover spaghetti or even linguine—simply substitute 3 cups cooked pasta for the uncooked spaghetti.
1. Preheat oven to 400°F. Cook spaghetti in large pot of boiling salted water according to package directions.
2. Meanwhile, heat 1 Tbs. oil in saucepan over medium-low heat. Add garlic, oregano, and rosemary. Sauté 1 minute. Remove from heat; mix in marinara sauce.
3. Whisk together eggs, Parmesan, and basil in bowl; stir in 2 Tbs. pasta cooking water. Drain pasta in colander, rinse with cold water, and drain again. Stir pasta into egg mixture.
4. Coat large ovenproof nonstick skillet with cooking spray. Add remaining 1 tsp. oil, and heat over medium-high heat 2 minutes. Add egg-pasta mixture to skillet; spread evenly. Cover, and bake 6 to 8 minutes, or until set.
5. Remove frittata from oven, drop 1 cup herb-infused marinara sauce over top of frittata by spoonfuls, leaving space between drops, and sprinkle with mozzarella. Cover, and bake 2 minutes more, or until mozzarella melts.
6. Loosen frittata from skillet using heat-proof spatula. Slide out onto platter. Serve with remaining sauce on side.