Preheat the oven to 375°F. Spray a 9x13-inch baking dish with non-stick spray.
In a large bowl, combine the ricotta, 2 cups Italian blend cheese, spinach, Parmesan, eggs, garlic, salt, and red pepper flakes.
Pour 1 cup marinara sauce in the bottom of the baking dish.
Spoon a heaping ½ cup of filling onto a crepe, forming it into a log, then roll up without folding in the sides. Place the manicotti in the prepared pan, seam side down. Repeat with remaining crepes.
Top with 1 cup sauce down the middle of the manicotti, then sprinkle with 1 cup Italian blend cheese.
Cover the pan with foil and bake for 25 minutes, or until hot, bubbling, and the cheese is melted.
Cool slightly and serve with salad and garlic bread.
6 servings