Remove papery outer skin from garlic (do not peel or separate cloves). Cut tops off of garlic bulbs; brush bulbs with half the oil. Wrap each bulb in heavy-duty foil. Bake at 425° for 30-35 minutes or until softened. Cool for 10-15 minutes.
Meanwhile, place spinach in a greased 11-in. x 7-in. baking dish; sprinkle with half the salt and pepper. In a large skillet, brown chicken in remaining oil on both sides; place over spinach.
In a large saucepan, melt butter. Stir in flour until smooth; gradually add milk. Bring to a boil; cook and stir for 1-2 minutes or until thickened. Stir in 1 cup cheese, nutmeg and remaining salt. Transfer to a blender; squeeze softened garlic into blender. Cover and process until smooth. Pour mixture over chicken.
Cover and bake at 425° for 30-35 minutes or until a meat thermometer reads 170° and sauce is bubbly. Uncover; sprinkle with remaining cheese. Bake 5 minutes longer. Serve with pasta. Sprinkle with tomato and parsley if desired. Yield: 2 servings.