Muddle one grapefruit peel with the simple in a mixing glass. Add the liquors and ice. Stir. Strain into a chilled coupe. Garnish with the other grapefruit peel.
This is obviously a riff on Nicholas Jarrett's Black Cat.
We were coming up with the drink menu for my daughter's wedding and wanted to get get as close as we could to a Black Cat using just one gin.