A breakfast martini is a cocktail made with gin, marmalade, orange liqueur, and lemon juice (in place of vermouth). The drink was invented in 1996 by bartender Salvatore Calabrese at a hotel in London.
It is similar to a White Lady cocktail, with gin, orange liqueur and freshly squeezed lemon juice; some variants of it even call for an egg white, though that is not included in the original recipe.
Add all the ingredients into a shaker with ice and shake vigorously until well-chilled.
Double-strain into a chilled coupe glass.
Garnish with a lemon wheel.