My third comment on this site, and my second recommending maple syrup (dial it back) instead of simple syrup. A go-to drink for something not-too-serious but seriously tasty.
Vertical Stall
Old Tom gin, Maraschino liqueur, Crème de cassis, Mezcal, Lemon juice
Makes me want to start a series called "Does It Flip?": take a classic cocktail recipe, add an egg, shake, and find out the answer!
My unsolicited advice: sub maple syrup (half the amount, maybe less!) for the simple. Adds to the complexity and helps it last longer!