Add the cinnamon sugar to one small plate and the caramel sauce to the other.
Dip the rim of the cocktail glass into the caramel sauce. Hold the glass over the sauce upside-down for a few seconds, so any excess will drip back onto the plate instead of down the side of the glass.
Dip the caramel-coated rim into the cinnamon sugar so that it sticks to the caramel all the way around the glass. Set the glass aside.
Using a sharp paring knife, cut your apple slice and make a small notch in the side of the apple slice. This will be where you attach the apple to the rim of the glass. Set the apple slice aside.
Cocktail
Add the applejack to your serving glass, being careful not to disturb the sugared rim.
Add in the apple cider to the glass.
Open your sparkling wine and pour it into the glass.
Add the apple slice to the rim of the glass, and serve.
Notes
You can omit the applejack if you want to make a lower-alcohol drink. If you do, I suggest using a spiced apple cider rather than plain apple cider.