Make the brown sugar syrup. In a small saucepan over medium heat, combine the dark brown sugar and water. Stir gently until the sugar dissolves completely—you’ll see the liquid turn a deep amber colour and smell a rich, toasty sweetness. Bring it to a gentle simmer and let it bubble for 2 minutes. The syrup should thicken slightly and coat the back of a spoon. Remove from the heat and stir in the vanilla extract and a pinch of flaky sea salt. Set aside to cool for a minute.

Prepare your glass. Pour the warm brown sugar syrup into the bottom of your serving glass. Tilt the glass slightly as you pour so the syrup coats the bottom evenly. You want a solid, glossy layer about half a centimetre deep.

Fill with ice. Add a handful of large ice cubes directly on top of the syrup. The cold ice will help set the syrup in place, preventing it from mixing too quickly. You’ll hear a satisfying crackle as the ice meets the warm syrup—that’s a good sign.

Pour the oat milk. Slowly pour the chilled oat milk over the ice. Pour it down the side of the glass to preserve the layers. The milk will sit above the syrup, creating a soft, creamy white band. You should see a clear separation between the dark syrup at the bottom and the milk above.

Add the espresso. Brew your espresso or strong coffee and let it cool for about 30 seconds. Then, pour it slowly over the back of a spoon held just above the surface of the milk. This technique—called layering—keeps the coffee on top. You’ll see a dark, rich brown crown form above the white milk, with the syrup glowing amber at the base.

Garnish and serve. For a restaurant-quality finish, place a cinnamon stick or a star anise on the rim of the glass, or drape a thin strip of orange zest over the edge. Serve immediately, and encourage your guests to stir the drink just before drinking to blend the layers.