Not just a variant of the Negroni, but also of the White Negroni. It was created by Matthias Lataille and Simon Difford in 2014 at the Cabinet Room in London, England. Half the gin is replaced with Cognac.
Half-fill a mixing jug with ice.
Add all ingredients and stir until well-chilled.
Strain into an Old Fashioned glass over fresh ice.
Garnish with a link grapefruit twist.