To prepare bread pudding sauce:
In a large microwaveable bowl combine sugar, 2 cups water, cinnamon, & butter. Bring to a boil in microwave. Stir in cornstarch with the remaining 1/4 cup of water and cook on high for a couple of minutes. Stir the sauce frequently until the sauce is clear. Remove from heat and add rum. Sauce will be thin. (taste sauce and add rum if you think it needs more)