1. Preheat the oven to 375oF. Divide muffin papers in the wells of the muffin tin. Cook the macaroni according the package directions until al dente, drain and set aside. Meanwhile, bring another pot of water to a boil. Cut the cauliflower into florets and cook until tender, 5 minutes.
2. Drain the cauliflower and place into a large bowl. Puree the cauliflower with a hand blender until smooth and set aside.
3. Melt the butter in a saucepan over low heat. Whisk in the flour and cook for 3 minutes, mixing frequently to create a roux. Gradually whisk in the milk, continue to stir until the mixture comes together and a thick white béchamel sauce forms, about 1 minute.
4. Pour the béchamel sauce into the cauliflower puree and mix together. Add 2/3 of the cheese and season with nutmeg, salt (in moderation) and pepper. Slice the meat from the chicken. Add the macaroni to the cauliflower-cheese sauce and fold in the chicken. Divide the mixture evenly between the muffin papers, filling them into a high mound. Sprinkle the tops of the muffins with remaining cheese.
5. Bake the mac and cheese muffins on the middle rack until golden brown, about 15 minutes. Remove the muffin tin from the oven and serve.
Per serving: 243 calories, 12g fat, 6g saturated fat, 44mg cholesterol, 172mg sodium, 18g carbohydrate, 1g fiber, 2g sugar, 16g protein