Combine brown sugar, water, cinnamon, and a pinch of salt in a small saucepan and heat until the sugar dissolves into a smooth syrup.
Pull two shots of hot espresso and immediately pour them over the syrup to help blend the flavors.
Add espresso, syrup, and ice to a cocktail shaker or jar, then shake vigorously for 20–30 seconds until frothy, chilled, and lightly foamy.
Fill a glass with fresh ice and strain the shaken espresso mixture into the glass, letting the foam settle beautifully on top.
Pour your choice of milk over the espresso, swirl gently, and serve immediately for the best flavor and texture.