Wild Mushroom and Spinach Stuffed Shells

Ingredients

6 ounces jumbo shell pasta (20 shells)

1¾ teaspoons kosher salt, divided, plus more for cooking pasta

3 tablespoons olive oil, divided, plus more for baking dish

1 medium yellow onion, chopped

3 cloves garlic, chopped

1 28-oz. can crushed tomatoes

¾ teaspoon freshly ground black pepper, divided

8 ounces sliced mixed wild mushrooms (such as shiitake, oyster, and cremini)

5 ounces baby spinach, roughly chopped (5 cups)

1 16-oz. container whole-milk ricotta cheese

1 cup grated Parmesan cheese

Preheat oven to 400°F. Cook shells in boiling salted water according to package directions for al dente pasta. Drain.

Heat 1 tablespoon oil in a large skillet over medium. Add onion and garlic; cook, stirring often, until softened, about 5 minutes. Stir in tomatoes, 1½ teaspoons salt, and ¼ teaspoon pepper. Cook, stirring often, until slightly thickened, 6 to 8 minutes. Reserve ½ cup sauce. Spoon remaining sauce into a lightly oiled 13-by-9-inch baking dish.

Wipe skillet clean and heat 1 tablespoon oil over medium-high. Add mushrooms and remaining ¼ teaspoon salt and ½ teaspoon pepper; cook, stirring occasionally, until browned, about 5 minutes. Transfer to a bowl. Add remaining 1 tablespoon oil to skillet. Add spinach and cook, tossing, until wilted, about 1 minute.

Stuff shells with ricotta, mushrooms, and spinach and arrange in baking dish. Top with reserved cup ½ sauce and Parmesan. Bake until shells are heated through and cheese is melted, 12 to 15 minutes.