Chill the apple cider and sparkling water before preparing the drinks.
Combine the granulated sugar and cinnamon for the rim on a small shallow plate.
Spread a very thin layer of caramel around the rim of each glass.
Dip the rims gently into the cinnamon-sugar mixture.
Fill each glass approximately halfway with ice.
Divide the apple cider between the two glasses.
Add 1 tablespoon caramel sauce to each glass and stir until mostly incorporated.
Divide the lemon juice between the glasses.
Add a small pinch of cinnamon to each glass.
Slowly pour the sparkling water over the cider mixture.
Stir gently to combine without removing too much carbonation.
Garnish each glass with a thin apple slice and optional cinnamon stick.
Serve immediately.