Preheat your oven to 375ºF. In a large pot, boil salted water, then add the jumbo shells. Cook them for about 10 minutes, just before they become fully tender. Drain and place the shells on a baking sheet lightly drizzled with olive oil to prevent sticking.

In a skillet, heat 2 tablespoons of oil from the sun-dried tomatoes over medium heat. Add the onion and garlic, sautéing for 3 to 5 minutes until soft. Pour in the broth and bring to a simmer, allowing it to reduce slightly for 5 to 6 minutes.

Add the cream, 1/4 cup of Parmesan, Italian seasoning, 1/2 teaspoon salt, 1/2 teaspoon black pepper, and sun-dried tomatoes. Let it simmer gently for another 4 to 5 minutes.

Squeeze excess moisture from the thawed spinach in a clean kitchen towel. In a mixing bowl, combine the spinach, ricotta, remaining Parmesan, lemon zest, and a sprinkle of salt and pepper; mix everything together thoroughly. Stuff each shell with this delicious filling.

Spread half of the sun-dried tomato sauce in a 3-quart baking dish. Arrange the stuffed shells on top and drizzle with the remaining sauce. Top with mozzarella cheese.

Cover with foil and bake for 15 minutes. Remove the foil and continue baking until the cheese is bubbly and melted, approximately another 15 minutes. Let it sit for 5 minutes before serving. Enjoy!