Melt the butter in a pan, and stir in the garlic and flour.
Pour the milk into the pan, and stir in the cream cheese. Now add about 5 oz of the grated cheddar cheese and stir once more, until the cheese is completely melted.
Place the cooked cauliflower into a casserole dish and pour in the cheese sauce. Add the bacon, salt, and pepper and mix everything together.
Finally, sprinkle the rest of the cheese on top, along with a bit more bacon and chopped spring onions. Now bake at 320 °F for 40 minutes.