1 pound squash, cut up and cooked tender
1/2 stick butter or margarine, softened, plus more for pan
1 teaspoon sugar
1 egg
1/2 cup mayonnaise
1/4 cup green pepper, chopped
1/2 cup chopped onion
1 small jar pimentos
1 teaspoon salt
1 (8-ounce) can sliced water chestnuts, drained and roughly chopped (optional)
1 cup grated cheddar cheese

Drain cooked squash and mash with butter or margarine. In a separate bowl, mix sugar, egg, mayonnaise, pepper, onion, pimentos and salt. Add to squash. Pour into buttered casserole dish; top with cheese. Bake at 350 degrees for 35 to 40 minutes.
Note: Peppers and pimento may be omitted if desired. Frozen squash may also be used.