1-First Step: Preheat the oven to 375°F (190°C). Bring a large pot of salted water to a rolling boil while you prepare the filling and sauce. Set up a baking dish (9×13-inch or similar), spoon marinara into the bottom to create a thin layer, and oil the dish lightly. If using fresh spinach, wash and roughly chop it; if using frozen, thaw and squeeze out excess water.

2-Second Step: Add the jumbo pasta shells to boiling water and cook for 8 10 minutes until al dente; they should still hold shape because they will finish cooking in the oven. Drain and lay shells on a sheet pan or tray in a single layer so they are easy to fill and won’t stick together. For a related guide on pasta tips, check out our blog section.

3-Third Step: Heat 2 tablespoons olive oil in a skillet over medium heat. Add minced garlic and sauté 30 45 seconds until fragrant, then add fresh spinach and cook until wilted (2 3 minutes) or heat frozen spinach until warmed through. Transfer to a bowl and let cool slightly, then squeeze out extra moisture and chop finer if needed.

4-Fourth Step: In a large bowl combine 1 1/2 cups ricotta, 1 cup shredded part-skim mozzarella, 1/2 cup grated Parmesan, the cooked and squeezed spinach, 1 beaten egg, 1/4 teaspoon nutmeg, salt and pepper to taste. Mix until evenly combined. For vegan or egg-free versions, substitute blended firm tofu plus vegan ricotta and omit the egg or use a commercial egg replacer.

5-Fifth Step: Using a spoon or piping bag, fill each cooled shell with about 2 3 tablespoons of the ricotta-spinach mixture. Place each stuffed shell seam-side up in the prepared baking dish over the layer of marinara. Arrange snugly but without crowding; you may need two dishes depending on quantity.

6-Sixth Step: Spoon additional marinara over the filled shells so they are partially covered; sprinkle remaining mozzarella and additional Parmesan over the top. Drizzle a little olive oil and scatter fresh basil or chopped parsley if desired.

7-Seventh Step: Cover the dish tightly with foil and bake in the preheated oven for 20 minutes. Remove foil and bake another 8 12 minutes until cheese is bubbling and slightly golden. If you prefer a crispier top, broil for 1 2 minutes while watching closely.

8-Eighth Step: Let the stuffed shells rest 5 10 minutes out of the oven so the filling firms and the juices redistribute. Garnish with extra grated cheese, a sprinkle of red pepper flakes, or a drizzle of high-quality olive oil. Serve warm with a green salad or crusty bread.

9-Final Step: To make ahead, assemble shells in the baking dish, cover tightly and refrigerate up to 24 hours before baking; add an extra 5 10 minutes to the bake time if baking cold. For freezing, assemble in a freezer-safe dish, freeze uncovered until solid then wrap tightly and store up to 3 months; bake from frozen at 375°F (190°C) for 40 50 minutes, covered for most of the time, then uncover to brown.