Put the blackberries in a bowl and mash them with a fork until broken up. Add the jam and mix until combined.
Spoon the blackberry mixture into the crust. Top with the whipped topping and serve.
Preheat the oven to 350 degrees F.
In a medium bowl, combine cracker crumbs and sugar. Add the butter and stir until combined. Press the crust into the bottom and up the sides of a 9-inch deep-dish pie plate. Bake for 7 to 8 minutes. Cool completely before filling.