Vanilla Sauce

This is a wonderful sauce for bread pudding.

1/2 cup granulated sugar
1 tablespoon cornstarch
1 teaspoon vanilla extract
1 cup boiling water
2 tablespoons butter
1/4 teaspoon salt

Mix sugar and cornstarch. Add boiling water, stirring constantly. Boil for 5 minutes. Remove from heat. Add butter, vanilla extract and salt.