1 In a large saucepan, bring the pears, water, lemon juice, granulated sugar, brown sugar, and bay leaf to a boil over moderate heat.
Lower the heat and simmer, uncovered, for 25 minutes or until the pears are very tender.
Let cool.
Remove and discard the bay leaf and stir in the vanilla.
2 Transferthe mixture to a food processor or blender and whirl for 1 minute or until pureed.
Pour into an 8"x 8"x 2" pan, cover with plastic food wrap, and freeze for 2 hours or until the center is almost frozen.
Remove the mixture from the freezer and beat until smooth
Return to the freezer for 45 minutes, then beat until smooth again.
Freeze 2 to 3 hours more or until firm.