Add the sugar and water to a small saucepan and bring to a boil, stirring until the sugar is dissolved. Once dissolved, set aside and add the rosemary sprigs and let it cool. Strain before using.
Make the Spritzer:
In a cocktail shaker, combine the tequila, orange juice, simple syrup with ice and shake.
Strain into glasses and top with champagne and a sprig of rosemary!
The recipe for the simple syrup will make more than what you need to serve two. If you are only serving two, I would half the recipe but I figure many will be making this for a group! If using Monk Fruit, this will crystallize if not used immediately. So if you want to have extra syrup on hand, I would recommend using real sugar and you can keep stored in the fridge for one month.