Cook shells to al dente as directed on the box.
Preheat oven to 350° F.
Spread shells out onto a baking sheet to dry (you may need to flip them over after a while to ensure they dry completely).
Meanwhile, thaw spinach by cooking in the microwave for 5-6 minutes (or follow package directions); drain all excess water.
In a medium bowl, mix together spinach, ricotta cheese, Parmesan cheese, salt, pepper, and garlic powder.
Spoon a small amount of sauce into a 9X13 inch baking dish. Fill each shell with spinach filling and place into the baking dish, open side up.
Shred the mozzarella cheese.
Top off with remaining sauce and cheese; bake for 15-20 minutes.
Serve with chilled grapes on the side. (Serving size: 3-4 shells, 1/2 cup grapes)