1 (15 ounce) package pastry for a 9-inch pie crust
2 tablespoons butter, softened, divided
Preheat an oven to 425 degrees F (220 degrees C). Set out four ramekins measuring 4 inches across the tops.
Combine the sugar, cornstarch, salt, and 1 1/4 teaspoons cinnamon. Place the mixed berries in a bowl. Sprinkle the mixture over the berries and toss gently to coat. Sprinkle lemon juice over the berries.
Cut out pie tops from the prepared crust by turning a ramekin upside down on the crust. Cut out four 4-inch circles of dough using the ramekins as a guide.
Pour 1 cup of berry mixture into each ramekin, making sure to scoop up plenty of the sugar and spices with it. Reserve the remaining berry mixture.
Dot each filled ramekin with butter, and top with the pie crusts. Cut four slits in each crust. Place the ramekins on a baking sheet.
Bake in the preheated oven until the crust is golden brown and the filling is bubbly, about 30 minutes.
Mix the remaining 1/4 teaspoon cinnamon into the reserved berry mixture. Microwave for 1 minute to make a berry sauce; stir. Serve the pies with the berry sauce.