----------------------------------GARNISH---------------------------------Thinly sliced lemon peel, halved and twisted FOR CRUST: Preheat oven to 350 F. Butter 9-inch springform pan. Blend crumbs and melted butter in bowl. Press mixture into bottom and up sides of prepared pan. Bake 5 minutes. Cool. FOR FILLING: Preheat oven to 350 F. Using electric mixer, beat cream cheese until soft. Gradually blend in sugar. Beat in eggs 1 at a time. Mix in lemon juice, lemon peel and vanilla. Pour into crust. Bake until slightly puffed, about 40 minutes. Maintain oven temperature at 350 F. FOR TOPPING: Blend all ingredients in small bowl. Spread on top of cake. Bake 15 minutes; topping will not look set. Cool 30 minutes. FOR GLAZE: Combine water, lemon juice and yolk in heavy small saucepan. Stir in sugar, cornstarch, and salt. Bring to boil over low heat, stirring constantly, about 10 minutes. Add butter and lemon peel and stir until butter melts. Cool glaze for 20 minutes. Spread glaze on cake. Cool completely. Refrigerate until well chilled. (Can be prepared 2 days ahead.) Garnish with lemon slices. Serve cold.