MIX sugar and gelatine in medium saucepan; stir in water. Let stand 1 min. Cook on low heat 5 min. or until gelatine is completely dissolved, stirring constantly. Add cocoa; stir until cocoa is dissolved. Remove from heat; cool. Add yogurt and vanilla; mix well. Gently stir in whipped topping. Pour into 9-inch square pan. Freeze 1 to 2 hours or until ice crystals form around edges.
SPOON into large bowl; beat with electric mixer on low speed 30 sec., then on high speed 2 min. Return to freezer. Freeze 2 to 3 hours or until firm. Meanwhile, preheat oven to 350°F. Gently press tortillas into 8 (10-oz.) custard cups to form cups. Bake 10 to 15 min. or until crisp; cool.
REMOVE yogurt from freezer at least 20 min. before serving to soften slightly. Scoop evenly into tortilla cups; top with the raspberry puree. Store leftover yogurt in freezer.