Adapted from Cook’s Illustrated Magazine, Summer Entertaining Issue, August 2009
For the graham cracker crust:
1 package graham crackers (9 crackers), crumbled
2 Tbl sugar
5 Tbl unsalted butter, melted
For the berry filling:
9 oz (about 2 cups) raspberries
11 oz (about 2 cups) blackberries
10 oz (about 2 cups) blueberries
1/2 cup sugar
3 Tbl cornstarch
1/8 tsp salt
1 Tbl lemon juice
2 Tbl red currant jelly
For the whipped cream:
1 cup heavy cream
1 Tbl sugar
1 tsp vanilla
For the graham cracker crust: Preheat the oven to 325ᵒF and arrange a rack in the middle of the oven. Place the crumbled graham crackers in the bowl of a food processor, and pulse until finely ground. (If you don’t have a food processor, place the crackers in a large zip-lock bag, then crush the crackers with a rolling pin.) Add the sugar and melted butter and pulse or stir until well combined. Evenly press the mixture into the bottoms and sides of a 9-inch glass pie plate, forming a neat border around the edge. Bake until the crust is set and golden, about 15-18 minutes. Set aside on a wire cooling rack.
For the berry filling: In a food processor, combine 2 1/2 cups of the berries until smooth and fully pureed, about 1 minute. Strain the puree through a mesh sieve into a small saucepot, pressing on the seeds to extract as much juice as possible. (You should have between 1 1/4 and 1 1/2 cups berry puree.)
In a small bowl, whisk together the sugar, cornstarch and salt, then whisk this mixture into the berry puree. Over medium heat, bring the puree to a boil, stirring constantly with a wooden spoon. When the mixture reaches a boil and thickens to a consistency similar to pudding, turn off the heat, stir in the lemon juice, and set aside to cool slightly.
While the puree is cooling, place the remaining berries in a medium mixing bowl. In another small saucepot, heat the jelly over low heat until it melts into a liquid. Drizzle the melted jelly over the mixed berries, and toss them gently to coat with the jelly glaze.
Pour the slightly cooled berry puree mixture into the cooled pie crust. Top with the jelly-glazed berries. Loosely cover the pie with plastic wrap and refrigerate until the puree has set and the pie is cold, about 3 hours or up to 1 day.
For the whipped cream: Whip the cream to soft peaks (When you stick a spoon into the cream and lift it out, a point will form then droop down after a second or two). Add sugar and vanilla and whip to firm peaks (The point formed in the cream will stand straight up and not fall over).
Cut the pie into wedges and top each slice with a generous dollop of whipped cream.