Brew two shots of espresso (18g in, 36g out in 25-30 seconds) into a small cup. 2. In a separate small bowl, dissolve 2 tablespoons packed brown sugar in 2 tablespoons hot water (200°F/93°C) until no granules remain. 3. Pour the brown sugar syrup into a shaker or mason jar. 4. Add the hot espresso to the shaker. 5. Fill the shaker with 6-8 ice cubes (about 1 cup). 6. Secure the lid tightly and shake vigorously for exactly 12 seconds — you should hear the ice clattering and see the shaker become frosty. 7. Pour the entire contents (ice and all) into a tall glass. 8. Top with 4 ounces (120ml) cold milk, pouring gently over the back of a spoon to preserve the foam layer. 9. Serve immediately with a straw.