(courtesy of Recipe Girl Lori Lange. Makes one 9-inch pie)
2 pie crusts (I like to use The Pioneer Woman's Perfect Pie Crust recipe, found at Thepioneerwoman.com)
2½ cups raspberries
2½ cups blueberries
½ cup sugar
3 tablespoons cornstarch
Roll out one crust to make a 12-inch circle. Snuggle it gently into a 9-inch pie plate and trim around the rim of the plate. Place the crust-lined pie plate in the refrigerator until you add the berries.
In a large bowl, combine the berries. In a separate small bowl, whisk together the sugar and cornstarch. Sprinkle it over the berries and gently toss. Let sit for about 10 minutes. Preheat the oven to 375 degrees F. Place a rimmed baking sheet in the oven on the center rack.
Pour the berry mixture into the chilled piecrust. Roll out the second piecrust and place on top. Trim the edges of the top crust and press together around the edges of the pan with the bottom crust. Cut vents in the top to allow steam to escape. (Alternately, cut strips from the second piecrust and make a patchwork pattern on top).
To bake, cover the edge of the pie with foil to prevent over-browning. Set on the heated baking sheet and bake for 25 minutes. Remove foil and bake for an additional 20 to 30 minutes, until the pie is golden and the berry juices are bubbling. Let cool.