Begin with the syrup. Add all ingredients to a pan and dissolve the sugar over a low heat. Once dissolved, bring to the boil, and boil 3-5 minutes or until syrupy. Remove from the heat and allow to cool to room temperature.

Once cool, strain into a bottle, discard the solids and store in the fridge for up to 2 weeks.

When ready, add the oat milk and syrup to a small pan and bring to steaming point whilst whisky to aerate the milk.

Pour the espresso into a mug, top with the warm milk and serve.