Cut cauliflower into florets and place into a large pot with about 1 inch of water. Bring to a boil, then reduce heat to medium and cook an additional 5-10 minutes, until the cauliflower is just tender.
Drain cauliflower well. Return to warm empty large pot for a few minutes to allow more moisture to be drawn out by the heat of the pot. Drain cauliflower again.
Add bacon to the pot and cook over medium heat until crispy. Remove bacon with a slotted spoon and drain on a paper towel lined plate. Pour out all but 2 tablespoons of the bacon grease from the pot.
Preheat oven to 350F.
Add garlic to the bacon grease in the large pot and sauté for about a minute, then add the heavy whipping cream. Heat cream to a simmer and add the shredded cheddar cheese. Stir until melted.
Remove pot with cheese mixture from the heat and whisk in xanthan gum until combined well. Season with salt and pepper.
Using your fingers or a fork, shred cauliflower into small macaroni sized pieces. Pour cauliflower into a casserole dish or cast iron skillet. Sprinkle bacon on top of cauliflower. Pour cheese sauce evenly over the cauliflower.
Bake until bubbly and browned on top, or for about 15-20 minutes.
Optional: Add additional shredded cheese to top and place under the broiler for just a couple of minutes.