Line an 8×8-inch square tin with parchment and grease generously with canola oil or nonstick spray. Set aside.

Add cold cranberry juice to a large saucepan; sprinkle gelatin over top to dissolve.

Add boiling cranberry juice and sugar to the saucepan and whisk to combine.

Bring mixture to a boil. Reduce heat to medium and simmer, stirring occasionally, until mixture reaches 107° C / 225° F on a digital thermometer. This will take 20-25 minutes or longer, so be patient!

Remove from heat. With a heat resistant spoon, stir gently to remove bubbles.

Pour mixture into prepared pan. Chill until firm, at least 4 hours or overnight.

Line a large tray with baking parchment and set aside.

Once set, peel away parchment and turn cranberry jelly slab out onto a well-sugared sugared surface. I like to use a chopping board covered in parchment, with 2-3 scoops of granulated sugar on top.

Coat the sticky slab in sugar. Use your hands to spread and distribute the sugar until the slab is completely covered on both sides.

Cut slab into squares with a sharp, well-oiled knife. (I like to lightly mark the squares with the back of my knife prior to cutting, to make sure all of my candies are roughly the same size.) You can cut 7 x 7 rows (for 49 square candies) or 8 x 8 rows (for 64 square candies). If preferred, you can also use a greased metal cutter to cut fun shapes instead of squares.

Roll each square in sugar so all sides are covered. Place coated candies on prepared tray, making sure they do not touch. Air-dry at room temperature, uncovered, for 1-2 days, or until candy crystallizes and develops a crunchy coating.

Store cranberry jelly candy in an airtight container, layered between sheets of parchment. These will keep well at room temperature for 3-4 weeks.