1. Preheat your oven to 400°F (200°C). In a large bowl, combine the mixed berries, sugar, cornstarch, lemon juice, almond extract, and green food coloring (if using). Mix gently until the berries are well coated. Pour the berry mixture into the unbaked pie crust. Dot the top with small pieces of butter. If using a top crust, cut it into strips and create a lattice pattern, or place a full crust on top and cut vents. Bake for 45-55 minutes, or until the crust is golden brown and the filling is bubbling. If the crust starts to brown too quickly, cover the edges loosely with aluminum foil. Let the pie cool completely on a wire rack before serving. This allows the filling to set properly.