I would leave them as they are for now. The heart will fill out in the weeks to come.

63 years of age. Never done gardening before. Don't know why I wasted the first 63 years of my life. But I thought people said it was relaxing. I go to bed each night worrying if my plants are OK in the dark, in the cold, on their own. Are all gardeners as mad as me. It's great fun!

Oh by the way. Thanks Ian.

Cauliflowers need to be extremely well fed to make a large plant before the flower comes. Stunted plants will never produce a good heart. Don't take the leaves off at any stage apart from if they go yellow, or when harvesting, as these feed the whole plant.
What affects them most is irregular watering or lack of water.
I'd always failed with them, getting a very small head, until this year, when I grew them in a polytunnel at a spacing of only one square foot. But I enriched the soil with compost and wood ashes, and gave each plant a handful of an organic fertiliser. They were watered every day. But of a dozen plants I had six huge caulis, three medium ones, and one small. One plant died. I've other plants outside which I'm watering well too but aren't ready yet.
If yours don't succeed, you should have another go with them aiming for a late autumn harvest as it's not too late to sow them now. Give them lots of water if there's a hot summer and you should get a good harvest in the autumn.

Just seen your comments Andydrive... yes we are all equally mad, especially with vegetables, as I have sleepless nights worrying about plants I haven't treated as I should! (I'm 64 and have been gardening for 30 years, and still keep trying different methods of growing things.)

Trying different methods, complete failure and the obvious triumph of putting a good hearty meal on the table is all part of the fun of veggie gardening. I don't think my dad has bought a veggie in about 200 years (I did tell you he was Noah's gardener, didn't I?) He rang me up on Sunday ranting away that his cauli's weren't producing properly and his spuds were behind schedule! Lol