Fill a 16 oz glass most of the way with ice. Pour in the cold brew and add the 2 tablespoons of caramel syrup; stir briskly until the syrup is dissolved and the coffee is evenly sweetened.
In a small jar or a frothing pitcher combine the whole milk, heavy cream, vanilla extract, ground cinnamon, and one pinch of sea salt. Close the jar tightly or cover the pitcher.
Froth the milk mixture until it triples slightly in volume and becomes velvety — about 20–30 seconds with an electric milk frother, or 40–60 seconds of vigorous shaking by hand. You want a thick, spoonable cold foam.
Use a spoon to layer the salted caramel foam over the iced cold brew, leaving a little room at the top. The contrast between the dark coffee and pale foam creates a nice visual and textural balance.
Finish with a teaspoon of caramel syrup drizzled over the foam and a very light pinch of flaky sea salt. Serve immediately with a straw or small spoon to enjoy both coffee and cream together.