Add the cauliflower to a pan of boiling water and cook for 10 minutes until soft.
Once the cauliflower is cooked, drain the water and add to a blender with the spreadable cheese, onion granules, garlic and mustard (you could also place in a separate bowl and use a hand blender). Blend until smooth and set aside.
While the cauliflower is cooking, add the pasta to another pan of boiling water and cook for 10 minutes or until tender.
Add the courgette to the empty pan that the cauliflower was cooked in and spritz with low calorie cooking spray. Gently sauté over a medium heat for 5 minutes until softened and cooked through. It should be as soft as the cooked pasta.
Pour the sauce into the pan with the courgette, along with the drained pasta and a few tablespoons of the pasta water. Stir to combine and season with salt and pepper to taste.
You can serve the dish like this, or make it extra cheesy by adding to an ovenproof dish and topping with the grated cheddar. Place under the grill for 5 minutes until the top is bubbling and golden and serve with an optional sprinkle of spring onion.