This is inspired by the cocktail "Jitterbug" from the Canon cocktail book, from Canon in Seattle WA. I was initially inspired to try the Jitterbug from buying a bottle of fernet, and testing different flavor combos to see what fit. The pairing of sweet vermouth, espresso, and fernet was addicting. Mr. black gave an opportunity to elevate the drink and further balance the flavors. The frenetic is a unique blend of savory, sweet, and musty.
Add all ingredients to a shaker (shaken so that the mr black will froth slightly and add some air/texture)
Shake with ice (I go 10-15 seconds)
Double strain into a chilled Collins glass, filled with ice. (Double strained for more air and to remove the ice chips)