01 -
Bring a large pot of salted water to a boil. Add the jumbo shells and cook until al dente, about 10–12 minutes. Drain and set aside, keeping them warm.
02 -
Heat the olive oil in a large skillet over medium heat. Add the chopped onion and cook until softened, about 3–4 minutes. Stir in the mushrooms and cook another 4–5 minutes, until they release their juices and begin to brown. Add the garlic and cook 30 seconds until fragrant.
03 -
Push the veggies to one side of the pan. Add the chopped shrimp to the empty side, season with a pinch of salt and pepper, and cook 2–3 minutes until just pink and opaque. Stir together with the veggies.
04 -
Reduce heat to low. Stir in the cream cheese until melted and smooth. Pour in the heavy cream and whisk until combined. Add ¼ cup of Parmesan and stir until melted into the sauce.
05 -
Stir in the chopped spinach and cook 1–2 minutes until wilted. Taste and adjust seasoning with salt and pepper.
06 -
Spoon the shrimp-spinach mixture into each pasta shell, arranging them in a single layer in a baking dish (about 9×13 inches).
07 -
Sprinkle the remaining ¼ cup Parmesan over the filled shells. Place under a preheated broiler for 2–3 minutes, or bake at 375°F for 8–10 minutes, until the tops are lightly golden and bubbly.
08 -
Garnish with chopped parsley if desired and serve hot.