Pour the whisky and amaretto into a mixing glass or jug. Add a large handful of ice, then stir with a long-handled spoon until the outside of the glass feels very cold. Taste to check the dilution, then fill a tumbler or rocks glass with ice.

Strain the cocktail into the ice-filled glass. Either drop in the strip of orange peel or, to make a twist, trim the ragged edges from the peel and twist into a spiral around a skewer. Hold for a moment, then release gently and drop into the glass.