I'm not a big fan of those, I find the よもぎ taste is too subtle and overpowered by the 粒あん inside. This might change next year if I can use more obscene amoungs of mugwort.
Traditionally, the もち dough is flavoured with the よもぎ, but I think it would be better to flavour the 中餡, using a little bit of white sesame paste as well to carry the flavour. The Chinese have a bun that uses mugwort and sesame, so this isn't completely out of place.
The recipe I found uses a mixed flour 求肥, flavoured with dried よもぎ and coloured green. However, next time, I'd just use a white normal 求肥 dough, and let the green filling be a surprise.
To incorporate the mugwort flavour: Blanch, make a paste.
🍸 However, since absinthe also uses mugwort, I'd just serve a Soufflé Mitterand instead, which is bound to be funner.
Traditional
If you want to make them like in the pictures, use a hand syrup (2:1 water:sugar) to make perfectly round 30 gr balls. Toss those into potato starch, then roll them out (like this they won't look as silly as this poor fella:)