1 orange creamsicle popsicle, to garnish (optional)
In a medium saucepan over medium-high heat, add the sugar and 1/2 cup of water. Cook for 5 minutes until the sugar is dissolved. Reduce the heat and simmer for 5 more minutes. Remove from heat and allow to cool completely. Add the tangerine juice, Cointreau and orange zest to the simple syrup. Stir to combine.
Pour the spiked tangerine juice into an 8x8 glass baking dish. Freeze for 6 hours to overnight.
In the bowl of a stand mixer fitted with the whisk attachment, whip the heavy cream until soft peaks. Add the sugar and whip to just under stiff peaks. If you wish, add 1 small drop of orange food coloring to the whipped cream. Beat on low speed to combine into a swirl.
In a small, shallow bowl, combine the sugar and orange zest. Dip the rim of the serving glass in water, then into the sugar mixture.
Remove the tangerine juice from the freezer and scrape with a fork into a granita. Scoop 1 cup of the granita into a serving glass. Add a splash of orange-scented soda water. Top with a hearty spoonful of the whipped cream. Serve with an orange creamsicle popsicle to make it really dreamy.