Cut squash crosswise into 1-inch slices; discard seeds.
Arrange in single layer in shallow baking pan; season with salt and pepper.
Cover and bake at 350° till almost tender, about 40 minutes.
In saucepan combine brown sugar, butter, and water; cook and stir till bubbly.
Spoon over squash.
Continue baking, uncovered, till squash is tender, about 15 minutes more, basting often.