In a sauté pan over medium heat add olive oil and red bell peppers, cook 3-4 minutes until softened, add in the artichokes and cook an additional 2-3 minutes. 

Add the baby spinach and stir. Season with salt and black pepper and cook for 2-3 minutes. Stir in the Alfredo sauce. 

In an oven - safe dish, cover the bottom of the dish with half of the sauce. Add the frozen stuffed shells to the baking dish. Cover the top of the stuffed shells with remaining sauce. Cover with foil and bake for 30-35 minutes.

Divide among serving plates and sprinkle with Parmesan cheese if desired.