I think it's done with a cake comb swirled around the cake then overpiped and airbrushed-- that's where I'd start --
Yes I agree with K8. Yaks lots of practice. Smear icing onn some parchment or wax paper to practice over & over :)
kakladi does it the civilized way on paper -- I used the counter top
Agree with what’s been posted. You can also use the tine’s of a fork to achieve the wavy lines. And guessing the butterflies are fabric, or paper that were purchased.