1. Preheat oven to 400°F. In 12-inch skillet, brown ground beef with onion and salt over medium-high heat; drain. Stir in chilies and 1/2 cup Ragú Pasta Sauce; set aside.
2. Meanwhile, evenly brush one side of 4 tortillas with half of the olive oil. On cookie sheets, arrange tortillas, oil-side down. Evenly top with 1/2 of the cheese, beef filling, then remaining cheese. Top with remaining 4 tortillas, then brush tops with remaining oil.
3. Bake 10 minutes or until cheese is melted. To serve, cut each quesadilla into 4 wedges. Serve with remaining sauce, heated.