"Internet" says mashed cauliflower freezes well
Based on several recipes, this is what I ended up doing using microwave, several cloves of garlic and food processor
Mashed Cauliflower
From Green Kitchen: So far I’ve found two awesome recipes that freeze well. They’re easy to make in large batches, defrost without any degradation, and are preparations of these foods that I actually love. One is the spiced applesauce I wrote about a little while ago.The other is mashed cauliflower.
1 large head of cauliflower (about 8 cups chopped)
1 Tablespoon butter
Salt and pepper, to taste
1) Chop cauliflower into florets.
2) Steam cauliflower until very tender, about 8-10 minutes. (Alternately, bring a large pot of water to a boil. Add cauliflower, and boil until tender. Timing here depends on the power of your stovetop to bring the cauliflower and water back up to temperature. Maybe 15-20 minutes? Or maybe my stovetop is weak.)
3) Drain cauliflower, and let cool until not too hot to touch. Pat cauliflower dry with paper towels.
4) Return cauliflower to pot, or to a big bowl, add butter, and puree with an immersion blender until creamy. (Alternately, puree in food processor.) Add salt and pepper to taste.
A note on this recipe: This is a very basic version. The options for embellishment are nearly endless. Anything you can do to mashed potatoes, you can do to this. Possible additions: roasted garlic, red pepper flakes, nutritional yeast, shredded cheese, olive oil, a little milk (cow, soy, or otherwise), paprika, scallions, roasted kale, sautéed zucchini, baked tofu, bacon, bacon bits, etc. I find that, just as with potatoes, a little fat goes a long way as long as the food’s thoroughly salted.
http://cheaphealthygood.blogspot.com/2010/11/green-kitchen-mashed-cauliflower-and.html