Easy Berry Cream Pie

1 10 oz. package fresh or frozen blackberries or strawberries (thawed if frozen)
*3 tablespoons blackberry or strawberry jam
1 8 oz. tub of Cool Whip whipped topping (or fresh whipped cream, if desired)
1 9 in. store-bought graham cracker piecrust

Place the berries in a bowl and mash until broken up. Add the jam and mix until combined. Spoon the blackberry mixture into the crust. Top with Cool Whip and serve.
Note: use the flavor of jam as the fruit