We very much prefer commenter Hyland's equal parts recipe offered in the comments section under the Paper Plane. As others have commented, this is too sweet.

Certainly not really reminiscent of a Paper Plane but it's a nice cocktail nonetheless, albeit on the sweeter side. The elderflower is front and center but the Nonino does a pretty good job of dialing it down. If I would remake it I'd probably use slightly less elderflower liqueur just to let the gin and Nonino speak a bit louder.

Based on the comments before me, I modified today's example to be:
- 40 ml gin (Beefeater)
- 20 ml elderflower liqueur
- 20 ml Amaro Nonino
and I think this is the direction in which to continue.
The next iteration would be:
- 45 ml gin
- 15 ml elderflower liqueur
- 20 ml Amaro Nonino

Also, given the total volume, a Nick&Nora glass would work well.

Far, far too sweet for me. I created two cocktails with the same Amaro Nonino, and St-Germain, and doubled the gin, and split it between two cocktails.

Delicious cocktail, although I find it is a bit farfetched to see it as "Paper Plane" variant. IMHO it needs a bit balancing as it is on the sweet side.