WHISK together evaporated milk and egg yolks in medium saucepan. Heat over medium-low heat, stirring constantly, until mixture is very hot and thickens slightly; do not boil. Remove from heat; stir in morsels until completely melted and mixture is smooth. Pour into large bowl. Refrigerate for 30 minutes until cool. Gently stir in 2 cups whipped topping.
REFRIGERATE for 2 hours until thickened. Sprinkle 1 cup raspberries over crust. Spoon chilled chocolate mousse over raspberries. Dollop remaining 1 cup whipped topping on center of pie; top with remaining raspberries.