Mix 1 cup of the cookie crumbs and the margarine. Press firmly onto bottom of 9-inch springform pan; set aside.
Place pumpkin, sugar and cinnamon in blender container; cover. Process until well blended; set aside.
Sprinkle gelatine over milk in small saucepan; let stand 1 min. Cook on low heat 3 min. or until gelatine is completely dissolved, stirring occasionally.
Add to pumpkin mixture in blender container; cover. Blend well.
Transfer pumpkin mixture to large bowl. Gently stir in 2 cups of the whipped topping.
Spread over crust. Refrigerate at least 1 hour. Top with the remaining 1/2 cup whipped topping just before serving.