1. Process first 6 ingredients in a blender 30 seconds or until very smooth. Cover and chill at least 2 hours or up to 2 days.
2. Pour mixture into freezer container of a 1 1/2-qt. electric ice-cream maker, and freeze according to manufacturer's instructions. (Instructions and times may vary.)
3. Whisk together lemon curd, sour cream, lemon zest, and lemon juice. Swirl lemon mixture and crushed meringue cookies into prepared ice cream. Freeze 1 hour before serving. Serve immediately, or transfer to an airtight container, and freeze up to 1 week.
*Vanilla extract may be substituted.
THE COOKIE: Gingersnaps, soft-baked from your bakery, for towering ice-cream cookie sandwiches. Wrap the finished treats individually (and tightly) in plastic wrap, and keep on hand in the freezer for parties or snacks.