Stir all ingredients over ice and strain into chilled Nick and Nora glass.
To make the banana oleo-saccharum, I cut the peels from two bright yellow bananas into 1/2" pieces and placed them in a small mason jar with 5 tsp granulated white sugar. The jar was sealed tight and left for 24 hours at room temperature before straining the resulting liquid through a coffee filter.
Attempting to recreate a wonderful cocktail from a recent outing to a local imbibery. The original featured tobacco bitters and madeira. Without those ingredients at home, I replaced the tobacco bitters with a dash each of Angostura and black walnut bitters, and the madeira with a half measure of Carpano Antica. Proportions of the original were unknown, but 2:1:1/4 felt right for this split-base, Manhattan/Boulevardier offshoot.
Adapted from a cocktail called Plátano served by Verdigris Bar in Leawood, Kansas.