I just used aged rum (Appleton specifically) and the result was truly wonderful. I genuinely feel it can be better than the vanilla infused rum. And yes, it tastes quite Toblerone-y and I think it's the combination of Amaretto and cream, plus the barrel aspects of the aged rum. Even the honey contributed some deep richness which I think can be used more in other creamy cocktails.

Didn't have amaretto used homemade vanilla extract and it was fantastic.

I had a okay around with this, firstly because I forgot to separate the white and yolk (was making flips last night!) and as I had a bottle of Krupnik, used that instead of rum and honey but matched their measurements. If anything using Krupnik made it taste smoother. But it still tasted just as good. I would say a wee bit better. Worth the experiment.