Heat 3/4 cup sugar til melted and caramel colored. Pour into 5 cups baking dish and swirl to line dish with caramel.Set aside. Beat egg yolks with 1/2 cup sugar.
Add evaporated milk and rum to taste and beat well. Turn custard into prepared baking dish. Place dish in pan of hot water and bake at 350 for about 1 hour or til knife inserted in center comes out clean. Cool thoroughly at room temperature, then unmold on serving plate. Serves 6 to 8