Preheat oven to 350°. In a small saucepan, heat sauce 5-7 minutes over medium heat or just until simmering, stirring occasionally., Spread 1/2 cup sauce into a greased 11x7-in. baking dish. Layer with half the ravioli, 1-1/2 cups spinach, 1/2 cup cheese and half the remaining sauce; repeat layers. Sprinkle with remaining cheese., Bake, uncovered, 45-50 minutes or until edges are bubbly and cheese is melted. Let stand 5 minutes before serving.