Preheat the oven to 425 degrees.
Cut the top off the head of garlic so the cloves are exposed. Then tear off a piece of foil, place your garlic head in the center, drizzle the top with a little olive oil, fold the foil around the garlic, put the whole package in an oven-safe dish, and roast in the oven for 45 minutes to an hour. When it’s finished, remove the garlic from the oven to cool.
Meanwhile, fill a medium sized pot with 1 cup of water and put in a steamer basket. Add cauliflower to the basket, cover pot, and turn the heat to medium. Steam the cauliflower until the florets are softened but not mushy, about 10 minutes.
Carefully remove the florets from the steamer basket and place them into a blender or food processor. Add ¼ cup of water from the steaming pot, the nutmeg, and some freshly cracked black pepper.
Then take your cooled head of garlic and remove the roasted cloves from the flakey husk. You can do this with your fingers or by smashing each clove with your hand over the flat side of a knife. Add the garlic to the blender and purée until the cauliflower mixture has a silky, sauce-like consistency. Use the cauliflower sauce immediately over pasta or on pizza. Or refrigerate for up to 3 days.