Cauliflower Mac n' Cheese- a healthy alternative

I got this recipe from Jamie Oliver.  I love it.  Its healthy, kids love it, and it freezes great.  Plus it makes a large amount of food in a small amount of time so if you're having last minute dinner guests or taking dinner to another family, its a great go to.

1/2 head cauliflower
8 oz cheddar cheese
4 oz parmesan
small bunch of italian parsley
1 lbs macaroni
1 cup creme fraiche or sour cream (I like plain greek yogurt)

1. To prepare your pasta: Remove the outer green leaves from the cauliflower and discard. Slice the end off the cauliflower stalk and cut the head into small florets. Halve the thick stalk lengthways, then slice thinly. Grate the Cheddar and Parmesan into a large heatproof bowl. Finely chop the parsley stalks and leaves.
2. To cook your pasta: Bring a large pan of salted water to a boil. Add the macaroni and all your cauliflower and cook according to the macaroni-package instructions. Place the bowl of cheese over the saucepan and add the crème fraîche. Carefully stir every so often until the cheese is smooth and melted. If the water boils up beneath the bowl, just turn the heat down slightly. Add all the chopped parsley to the melted cheese and season with a pinch of salt and pepper.
3. Carefully remove the bowl of cheese using a towel or oven gloves and put aside. Drain the macaroni in a colander over a bowl, reserving the cooking water. Return the pasta to the pan, pour in the melted cheese, and stir. It should have a lovely, silky consistency, but if it’s too thick for you, add a splash of your cooking water to thin it out a bit.
4. At this point you can either serve the macaroni as is, or finish it under the broiler to make it crispy and golden on top. To do this, preheat your broiler to a medium to high heat. Add ⅔ cup of the reserved cooking water to the macaroni, stir in, then transfer to a baking dish. Place under the broiler until golden and bubbling.
5. To serve your pasta: Divide the pasta between plates or bowls, or place the baking dish in the middle of the table next to a nice green salad and let everyone help themselves