Asking my daughter to reply (she has made quite a few of these plushies) : 

Hello ! :) I typically get the "pimple head" on patterns that start with a MC6, so not with the patterns from the book. I'll still try to help ! From what i could find, the "pimple head" is caused by a tension issue.

So first, i'd try to close the magic circle tighter if you can. I usually do 3 or 4, start tightening, and do the rest in the little space remaining. And then i tighten some more ! Careful, though, chenille tends to snap really easily. You want a longer tail than you would need for cotton or acrylic, so you can grab it easily and pull delicately.

If that doesn't work, i'd test the chain 2 method from the book. No tightening necessary !

If that is still no good, i'd go for more stitches in my MC. Like 9 or 10. Then you need to double that on the next round (so it lays flat), and then adapt the pattern until you reach the proper count. For example, if you had MC8, inc (16), 1 sc, inc (24), then (30) you could try transforming it into MC10, inc (20), then inc (30), and continue from the 30 round in the pattern. Or maybe MC9, inc (18), 2sc, inc (24) ? That might require a bit more experimentation to get the proper shape (i haven't tested it myself), but once you get something that works, you can use it on all patterns and get nice flat heads everytime. :)

Hope this helps some : these patterns are really worth it !