Bring a large pot of boiling water to a boil. Add a hefty pinch of salt and cook the shells for 9 minutes; they should still be firm and al dente. Drain and run under cold water to stop the cooking

Meanwhile, heat a large skillet on medium-high heat, add oil to coat the pan, then add the zucchini and a pinch of salt and sauté until most of the liquid has evaporated, about 5 minutes. Add spinach and cook with the zucchini for a minute or so, just until the leaves are wilted. Transfer the veggies to a large bowl

In the skillet, add the butter and garlic and cook, over medium-high heat, for 2–3 minutes until the garlic gets golden. Add tomatoes and about 1/4 pouch of Red Pepper Romesco and lower the heat. Cook, on low heat, stirring occasionally, for about 5 minutes

While the sauce cooks, add the ricotta, a squeeze of Romesco, and a pinch of salt to the veggie mixture and stir to combine. Fill the shells with about 2 Tbsp. of the veggie/ricotta mixture

Nestle the stuffed shells into hot sauce in skillet. Cover and cook over medium heat until shells are warmed through, about 5 minutes. Sprinkle with Parmesan