8 uncooked manicotti shells  | 
                                                1 1/2 cups part-skim ricotta cheese  | 
                                                1 cup (4 ounces) shredded part-skim mozzarella cheese  | 
                                                1/3 cup grated parmesan cheese  | 
                                                1 tablespoon chopped fresh parsley  | 
                                                1/4 teaspoon pepper  | 
                                                1 (10-ounce) package frozen chopped spinach, thawed and drained  | 
                                                1 large egg, lightly beaten  | 
                                                1 large egg white  | 
                                                olive oil-flavored cooking spray  | 
                                                2 1/2 cups marinara sauce  |