Remove the chicken sausage from casings and cook over medium heat, breaking into small bite size pieces with the back of a wooden spoon. Add onion, garlic and paprika and cook for 2 more minutes. Add tomatoes and basil, mixing in well and set aside.
Mix together ricotta cheese, parmesan cheese, beaten egg, Add chicken mixture and combine well.
Stuff cooked shells with chicken and cheese mixture and place in a baking dish.
Bring the oil to medium heat in a saucepot. Sweat the onions until translucent, about 3 minutes. Add the garlic and sweat until fragrant, about one more minute. Stir in the peppers and tomatoes. Simmer for 5 minutes. Working in batches, process the sauce on high in a food processor until smooth. Return the sauce to the pot, reduce the heat to low and whisk in the cream. Remove the heat an stir in the lemon juice. Season with salt and pepper.
Pour sauce over pasta shells and top with grated parmesan cheese. Bake at 350 degrees F for about 15 to 20 minutes or until bubbly and hot.