Heat marinara sauce in a saucepan over medium heat until bubbling; reduce the heat to low and simmer until needed.
Meanwhile, whisk egg and milk together in a small bowl. Whisk bread crumbs and salt together in a second small bowl.
Dip each ravioli in milk mixture, then in bread crumbs to coat.
Heat 2 inches oil in a large, heavy pan until a small amount of breading sizzles and turns brown. Fry ravioli, a few at a time, until golden, about 1 minute per side. Drain on paper towels.
Sprinkle warm ravioli with Parmesan and serve immediately with hot marinara sauce on the side.
Editor's Note
Nutrition data for this recipe includes the full amount of breading ingredients. The actual amount of breading consumed will vary. We have determined the nutritional value of oil for frying based on a retention value of 10% after cooking. The exact amount will vary depending on cooking time and temperature, ingredient density, and specific type of oil used.