Ricotta cheese and spinach are delicious together, but when you stuff them into tender pasta shells, top 'em with savory marinara and mozzarella, and bake until golden and gooey, you're doing dinner like a boss. Oh yeah, it's got garlic bread on the side because garlic bread.
Prepare two medium casserole dishes with cooking spray. Mince garlic. Finely chop spinach. Combine ricotta, Parmesan, spinach, liquid egg, ¼ tsp. salt, and a large pinch of pepper in a mixing bowl.
Cook Pasta and Make Marinara Sauce
Add 16 pasta shells (12 to fill and 4 just in case!) to boiling water and stir. Boil 9 minutes, drain in colander, and rinse briefly under cold water to prevent sticking. While pasta cooks, combine crushed tomatoes, half the garlic, oregano, 1 Tbsp. olive oil, and salt and pepper to taste in a mixing bowl. Spoon a thin layer of marinara sauce in bottom of prepared casserole dishes.
Fill the Shells
Hold shell open with one hand and, using a spoon, fill 12 shells with ricotta filling, about ⅔ full. If you have leftover filling, add more to filled shells. Place filled shells snugly in casserole dishes.
Bake the Shells
Top shells in casserole dishes with remaining sauce and mozzarella cheese. Spray two pieces of foil with cooking spray and place tightly over each casserole dish, sprayed side down. Place casserole dishes on prepared baking sheet, leaving room for bread in next step, and bake for 20 minutes.
Prepare the Bread
Halve baguette, then slice pieces again on an angle. Rub bread with remaining garlic and 2 tsp. olive oil. After shells have baked for 20 minutes, remove from oven, discard foil, place bread on baking sheet, and bake an additional 5-8 minutes, or until cheese is lightly browned and bread is toasted.
Plate the Dish
Remove baking sheet from oven and, using oven mitts and trivets, serve stuffed shells and garlic bread straight to the table. Filling will be hot, so take care when biting into shells!