Have a look at the little 'Unai's first day - behind the scenes' video.

[Sir C]

You poured the melted butter in while smooshing or poured it in and then smooshed?

These details are key.

Whilst smooshing. I sought assistance from tinternet and watched a video of a bloke doing it. He drizzled the butter in slowly whilst smooshing - I just sort of poured it in and it made no difference.