Combine first 4 ingredients; mix well.
Spread to 1/4 -inch thickness on an un-greased cookie sheet; bake at 350Â° for 20 minutes, stirring with a fork every 5 minutes to crumble.
Let cool; sprinkle half of crumb mixture in a 13- x 9- x 2-inch baking pan.
Set aside; reserve remaining crumb mixture.
Beat egg whites (at room temperature) until foamy.
Gradually add 1/2 cup sugar, 1 tablespoon at a time, beating until stiff peaks form.
Gradually stir in raspberries and lemon juice; fold in whipped topping.
Spread evenly in pan; sprinkle with reserved crumb mixture.
Freeze until firm.