This is from memory since I winged it twice, mashing two recipes together and adapting for liqueur. Putting Brancamenta in the filling is pretty gimmicky—the Fernet in the crust dominates—so you can skip it, just double the mint extract and up the sugar to 150g. You really ought to taste as you go and adjust sugar/liqueurs.
For the syrups, it is sufficient to just boil off the alcohol on the stovetop; you should boil off most of the water, too, it just takes a lot longer. Ethanol boils at 78°C/173°F, so you’ll know it’s done when the temperature rises above that. To crystallize, use either the stovetop or oven methods from alcademics (with the former you can easily burn the sugar, but you’ll be torching it later anyway; the latter is much easier to pull off. Hell, you should probably use it to make the syrup, too).
You will want your kitchen to be well-ventilated, in any case:
I might’ve fried my sense of smell doing this. It smells like a tanker truck of mentholatum crashed into an Indian restaurant.
— Joshua Yotty (@whynot) November 14, 2014Assemble 9″ springform pan and wrap bottom with aluminum foil. Use the foil even if you don’t bother with a water bath; springform pans easily leak, and you will have butter or syrup seepage. Finely grind Quadratini, chocolate and sugar in food processor. Add butter; blend until crumbs begin to stick together. Pulse in Fernet-Branca syrup a half ounce at a time, to taste. Press crumb mixture firmly onto bottom and 1¼″ up side of pan.
Preheat oven to 160°C/325°F. Beat cream cheese, sugar, and cornstarch in a large bowl until smooth. Add eggs and yolk; beat on low speed just until combined. Stir in the cream, extracts, and food coloring if using. Stir in Brancamenta reduction, to taste. Fold in chopped baking wafers, pour into crust.
Place in shallow water bath inside roasting pan and transfer to oven. Bake for 50-60 minutes or until center is almost set. Cool on a wire rack for 10 minutes. Carefully run knife around edge of pan to loosen. Let cool at ambient temperature for another hour then transfer to refrigerator overnight.
Sprinkle a slice with Brancamenta sugar mixture and brûlée with torch.