3 cupsor 1 jar(24 oz) pasta sauce (any flavor and variety)
Heat oven to 375 degrees F. Bring a pot of generously salted water to a boil. If using fresh spinach, quickly cook the spinach, remove with a slotted spoon (reserving the water), and drain well and then squeeze off excess water. Chop and set aside.For Frozen Spinach, thaw completely, drain and squeese out any excess water.
In the same pot of water, cook manicotti pasta shells as directed on the box. Rinse with cool water; drain well. Set aside
Meanwhile, in a large bowl, stir together 1-1/2 cups Italian cheese blend, red pepper flakes, ricotta cheese, prepared spinach, garlic powder, salt, and pepper. stir to combine and taste to check seasonings. Then add the egg and mix well.
In the bottom of an ungreased 13x9-inch glass baking dish, spread 1 cup of the pasta sauce. Pipe or spoon ricotta mixture into the manicotti shells; place on top of the sauce in baking dish. Repeat with remaining shells. Pour remaining sauce over manicotti and top with the reserved cheese.
Cover with aluminum foil and bake for about 30-minutes or until sauce is bubbling and hot. Uncover dish and bake uncovered 5 minutes longer or until cheese is melted, bubbly, and slightly browned.
You can make this recipe up to 24 hours ahead. Just cover and refrigerate until ready to bake. Add about 10-minutes to the baking time.This recipe is easily halved. In the case of the egg, still use one whole egg.