Chocolate frozen yogurt

3/4 cup sugar
2 teaspoons cornstarch
12 ounces evaporated lowfat milk
1 teaspoon vanilla
1 cup plain yogurt
2 ounces semisweet chocolate chips
In medium saucepan, combine the sugar and cornstarch. Stir in milk. Cook and stir over moderate heat until
thickened and bubbly. Remove from heat; let the mixture in the refrigerator. Add the vanilla and yogurt.
Refrigerate until the mixture is cold. Melt the chocolate. While the chocolate is hot, pour it very slowly into the
chilled yogurt mixture while stirring gently. Freeze in a ice-cream maker according to manufacturer's directions.