I wanted to do a version of the kale and cauliflower bake with either spinach and cauliflower or broc and instead of tofu use some of my 8 cups of chicken!
Can I use flax instead of Breadcrumbs?

Yes, you can. Let us know how it turns out, I've never had much luck with that recipe.

KO, are you in Phase 1? If not, you might want to consider using wheat germ instead of breadcrumbs. I've been very successful with that substitution. I wonder if the oil in the flax might cause it to make a somewhat wet/odd topping once heated?

I mix flax with wheat bran. that works fairly well.