In a large pot of boiling water, cook pasta until tender but firm. Drain
In a skillet, heat olive oil over medium heat; cook onion, green pepper and garlic until softened, about 6 mins. Transfer to a bowl; stir in sausage, egg and parsley. Place heaping 1 tsp in each of the shells. Arrange in greased 8-inch square glass baking dish.
In a bowl, stir together tomatoes,oregano and salt; spoon over stuffed shells. Sprinkle with mozzarella and Parmesan cheeses; cover and bake in 425F over for 20 mins.
Uncover and bake until cheese is golden brown.
Notes
You can use a ready made pasta sauce if you don't have a can of tomatoes or the spices