Prepare your jars by ensuring they are clean and lids are defect-free.
Set up your water bath, add the empty, covered jars to the bath and heat along with the water to 82ºC.
Make a caramel:
Add sugar to a clean saucepan and cook until you achieve a deep amber colour.
Remove jars from water bath and place on a towel. Remove lids and carefully pour in enough caramel to coat the bottom of each jar. Swirl the jar to coat the sides. Allow to set.
Make the custard:
Mix together, all the custard ingredients with an immersion blender, whisk or hand mixer. Pour evenly into each caramel-coated jar.
Cook the custard:
Attach lids, finger-tip tight and add to heated water bath. Cook for 1 hour.
Remove from water bath, and place on a towel-lined counter to cool at room temperature. Then transfer to the refrigerator to set for at least four hours, preferably overnight.
Plate and serve:
When ready to serve, remove from the refrigerator and allow to warm at room temperature for about 15 minutes.
Slide a thin palette knife around the sides of the custard to loosen from the jar. Invert the jar onto a plate to remove the flan from the jar. If it doesn’t slide out of the jar, apply a little heat to the bottom and sides of the jar, using a kitchen torch or heat gun on low setting.
Optional: finish off with a tuile or other topping of your choice, or simply enjoy, as -is.