Combine water and sugar in a medium sauce pan set over medium-high heat. Stir until sugar dissolves, then lower heat to medium-low and add cranberries. Cook.
Meanwhile, place remaining 1 cup sugar in a small bowl. Use a slotted spoon to carefully transfer a few cranberries at a time from the sauce pan and place in sugar. Swirl until evenly coated.
Fill a cocktail shaker halfway with ice, then add gin, elderflower liquor, cranberry simple syrup, and fresh lemon juice. Shake, then divide evenly into coupe glasses.
Garnish with fresh mint and candied cranberries.