In a large pot over high heat, boil water and prepare pasta shells as directed on package. Cook pasta shells only until al dente. The pasta will finish cooking when the dish is baked. Drain the pasta shells and set aside.
In a large bowl, combine the rest of the ingredients, except the 1/4 cup of cheese for the topping. Fill the pasta shells with the filling and place in a baking dish. Sprinkle the remaining 1/4 cup of cheese over filled shells.
Preheat oven to 350 degrees and bake shells uncovered for 30 minutes or until shells are bubbling hot and cheese melts.