Warm the cider: In a small saucepan over medium heat, warm the apple cider until steaming, not boiling.
Add a pinch of cinnamon and the vanilla if using. Stir gently.
Prepare the espresso: Pull 1–2 shots of espresso. If you don’t have an espresso machine, brew very strong coffee (about 1/3 cup).
Keep it hot.
Heat and froth the milk: In a separate pan or microwave, warm the milk until hot but not scalded. Froth using a handheld frother, French press plunger, or whisk vigorously to create foam.
Sweeten with caramel: Stir 1–2 tablespoons of caramel sauce into the hot cider until dissolved. Taste and adjust sweetness.
Combine: Pour the espresso into a large mug.
Add the caramel cider. Top with the hot milk, holding back the foam, then spoon the foam on top.
Finish: Drizzle with caramel, add a pinch of cinnamon, and a tiny sprinkle of sea salt if you like a salted note. Serve immediately.