Place the cauliflower florets in a food processor and process until you get finely grains. Place the cauliflower in a bowl along with the butter and mix until well combined. Set aside.
Chop bacon and place it in a frying pan on medium heat. Cook until bacon turns brown and crispy. Add bacon to the bowl with the cauliflower.
Place the spinach in the same frying pan and cook it with the bacon fat. Cook for about 1 minute and add spinach to the bowl with the cauliflower.
Add the mozzarella cheese along with chopped onion, salt, and pepper. Mix all the ingredients in the bowl until they are well combined. Shape the mixture into patties with your hands.
Add the oil to the frying pan on medium heat. Place the patties in the frying pan. Cook for about 2 minute each side and serve.