2 tablespoons cornstarch dissolved in 3 tablespoons Kahlua
Puree raspberries and strain to remove seeds. Add sugar, Kahlua and lemon juice
to the puree. Bring to a boil over medium-high heat and whisk in cornstarch mixture.
Cook until sauce thickens and runs clear, about 1 to 3 minutes.
Remove from heat and cool.
Cover and chill.
For each parfait, layer vanilla ice cream with chilled sauce (and, when available,