Bring this dessert out and your parents might just fall out of their chairs — it looks that good. No one will ever suspect that your main ingredient here is pudding out of a box. But don't get the instant kind — it tastes starchy and grainy — just stick to the "cook and serve" kind. It only takes about four minutes, so it's still a no-brainer. The fresh berries are the crowning jewels of this tart. They are always available in the supermarket but they're a lot cheaper when they're in season in the summer. If you can't find blueberries or strawberries you can substitute with a pint of fresh raspberries. The graham cracker crust is also as easy as it gets but it's a great complement for the custard and berries. You don't need a fancy tart pan for this. If you have one, great, otherwise just grab a large aluminum pie pan from the supermarket. They get the job done and come in handy for other desserts, so don't throw them away.
For the crust: crumble the graham crackers by hand or with a potato masher to get fine crumbs. Heat the butter in a saucepan or microwave until half-melted. Work the butter into the crumbs with your fingertips until the crumbs look like wet sand. Using your fingertips, press the crust into a 9-inch pie plate or disposable aluminum pie pan to make an even layer over the bottom and sides of the pan. Bake until the crust is a shade darker, about 12 minutes, and let cool completely.
Make the pudding according to the package directions. Let stand about 5 to 10 minutes stirring occasionally to keep a skin from forming on the top of the pudding.
Use a spoon or rubber spatula to scrape the pudding into the graham cracker shell and smooth it into an even layer. Put the tart in the refrigerator until the pudding is chilled and set, at least 1 hour.
Meanwhile, cut the stems off the strawberries and wash with the other berries in a colander under cold water. Drain then spread out on paper towel to dry. You can either arrange the berries nicely over the pudding or just sort of gently tumble them onto it. Cover the tart lightly with plastic wrap and refrigerate. You can make the tart up to 4 hours in advance. Serve cold.