Cranberry-Raspberry Jellies

Lightly coat an 8-inch-square baking pan with cooking spray. Line the pan with plastic wrap, allowing it to overhang by 2 inches on two sides. Lightly and evenly coat the plastic wrap all over with cooking spray (the candy will stick to any unsprayed areas).

Place 1/2 cup cranberry juice concentrate in a small bowl. Sprinkle gelatin over it and let stand, stirring once or twice.

Meanwhile, in a heavy, nonreactive (see Note) Dutch oven, stir together the remaining 1 1/2 cups cranberry juice concentrate, raspberries, cranberries, lemon zest, lemon juice and 3 cups sugar. Bring to a boil, stirring, over medium-high heat. Clip a candy thermometer to the pan, adjusting it so the tip is submerged but not touching the bottom. Boil briskly, stirring frequently, until the mixture cooks down slightly, 6 to 7 minutes. Lower the heat so the mixture boils gently and cook, stirring frequently, until it reaches 244 degrees F, about 25 minutes.

Remove from heat. Add the gelatin mixture (it will be very firm by now), stirring until it completely dissolves. Immediately pour the jelly mixture into a fine sieve set over a nonreactive bowl. Force through as much juice and pulp as possible using a heatproof spatula or wooden spoon; work briskly, as the mixture will thicken as it cools. Transfer the jelly to the prepared pan. Let stand, uncovered, on a cooling rack until completely set, 3 to 4 hours. Refrigerate for 4 hours, or overnight, to reduce the stickiness before cutting.

Generously dust a large cutting board with granulated sugar. Holding the edges of the plastic, lift the jelly out of the pan. Lay the slab top-side down on the board. Peel off the plastic. Sprinkle the slab all over with some of the remaining 2/3 cup sugar. Using a lightly oiled large sharp knife, trim off and discard the slab edges all around, forming clean edges. Cut the piece lengthwise and crosswise into eighths or tenths, forming individual jelly squares, cleaning and re-oiling the knife as necessary. Roll each square in sugar until coated on all sides. Let the jellies stand, uncovered, to dry for 4 hours, or overnight. Once dry, dust with additional sugar, covering all surfaces. Store the jellies, not touching each other, in single layers separated by wax paper (or in paper candy cups), in a flat, wax paper-lined storage container in the refrigerator. Serve at room temperature.