Preheat oven to 375 degrees. Cook Italian sausage in a skillet over medium heat, stirring often, 10 minutes or until sausage crumbles and is no longer pink, drain well. Stir pasta sauce into sausage.
Chop spinach and toss with pesto in a bowl.
Spoon 1/3 of sausage mixture (about 1/2 cup) into a lightly greased 11 x 7 inch baking dish. Top with half of spinach mixture. Arrange half of ravioli in a single layer over spinach mixture. Repeat layers once. Top with remaining sausage mixture.
Bake at 375 degrees for 30 minutes. Sprinkle with shredded cheese, and bake 5 to 8 minutes or until hot and bubbly.