You can find the pattern for these in 'Amigurumi World' by Ana Paula Rimoli.
I think the grey one is my favourite.
Hook :: 4mm and 3.5mm
Yarn :: Rowan Handknit cotton
Pattern :: Tiny ami cat by Ana Paula Rimoli. Ana's Patterns are also available on her blog and through her Etsy shop.
After making those I picked up this blanket again...
It's been sitting neglected in a box for a long time now, the reason being that I don't like the join-as-you-go method when the outer rounds are different colours. I find I spend too long dithering over what colour combination to make the next square as I don't want it to be too similar to the squares around it. I know that in the end it won't really matter, but still, I won't use this method of joining again unless all the squares are bordered in the same colour.