Grab a 1litre glass bottle and pour 700ml of Johnnie Walker Double Black, 300ml of simple syrup, 12 dashes of orange bitters and 110ml of water.
Seal the bottle and gently swirl it to mix the ingredients. Store the bottle in the fridge until ready to use.
When you are ready to serve, pour the cocktail into old-fashioned glasses and garnish it with an orange peel.