In a small bowl, combine 1/4 cup sugar, almonds and cornstarch; mix well. In a small mixing bowl, beat egg whites at high speed until foamy. Add cream of tartar; continue beating until soft peaks form. Gradually add remaining sugar; beat until stiff peaks form. Fold in almond mixture. Spread over the bottom and sides of a greased 9-in pie plate. Bake at 275 for 1 to 1 1/2 hours or until light golden brown. Turn off oven; do not open door. Let cool in oven for 1 hour. Remove from oven and cool completely. Meanwhile, for sauce, combine sugar and cornstarch in a medium saucepan. Gradually stir in water; mix until smooth. Add raspberries; bring to a boil over medium heat, stirring constantly. Boil 1 minute or until thickened; set aside. Cool. To serve, scoop ice cream onto meringue; top with mixed berries and sauce. Serve immediately. Store leftovers in the freezer.