Preheat oven to 500°F. Puree in a blender red peppers. You should have about 1 cup puree.
In a large bowl, combine the puree with canned tomatoes, heavy cream, Pecorino cheese, Fontina cheese, ricotta cheese, Italian sausages and 1/2 teaspoon salt.
Bring to a boil in a large pot 5 quarts water and 2 tablespoons salt. Add to the boiling water and cook until just tender pasta shells. Drain the pasta, add to the ingredients in the bowl, and toss to combine.
Divide pasta mixture among 6 to 8 individual gratin dishes (1-1/2- to 2-cups capacity). Dot with 4 tablespoons (1/2 stick) unsalted butter. Bake until bubbly and browned on top, 7 to 10 minutes.