Slice vanilla bean in half lengthwise (to expose the vanilla seeds) and cut in small pieces. Add the pieces to a skillet and cook over medium-low heat, stirring occasionally for about two minutes, until fragrant. When it starts to smell toasted, it’s ready. Set aside.

In a medium saucepan, bring water and sugar to a boil. Reduce heat to low, add toasted vanilla bean pieces, and simmer about 10 minutes, until sugar is completely dissolved and mixture has thickened a bit.

Pour syrup into a glass container. (It will continue to thicken as it cools.) For best results, keep vanilla bean pieces in the syrup. Strain when ready to use.

Fill a cocktail shaker with ice. Add espresso and vanilla syrup and shake well.

Fill a glass with ice. Add half the espresso mixture.

Shake the remaining half of the espresso mixture vigorously in the cocktail shaker for about 20 seconds, until frothy. Add to the glass.

Top with milk, letting it drip through the frothy mixture into the espresso beneath. Drink immediately.