Been making it a few times recently and found out how to make my OG recipe better...
I melt a handful of Nestle Butterscotch Chips or so with a double boiler and add it to the foam mixture, make sure you melt it fully or you'll get lumps of the chips. This makes the foam taste literally exactly like the WWOHP version. Once done with that, layer it on top of your base as usual and then finish with a milk frother if you have one (this makes the foam stick to the soda better so you get some of the foam and soda in each sip instead of just one or the other.