Prepare an 8x8 inch square baking pan by lining it with parchment paper and spraying it lightly with cooking spray.

In a heavy-bottomed saucepan, combine the fruit purée, granulated sugar, lemon juice, and optional butter. Cook over medium heat, stirring constantly until boiling, about 5-7 minutes.

Once boiling, stir in the liquid pectin and boil for exactly one minute while stirring continuously.

Pour the mixture into the prepared pan and allow it to cool at room temperature for 4-6 hours or overnight.

After setting, lift the jellies out of the pan and cut them into 1-inch squares. Toss each piece in granulated sugar.

Place the sugar-coated squares on a wire rack to dry for 1-2 hours.