Cook pasta according to package instructions. No need to add extra oil or salt at this point.
Wash the cauliflower, cut into large pieces, and boil until very soft. Drain the water and mash until very smooth. Mix the pasta and cauliflower in an 8×8 baking dish. Stir in the canola oil.
In a small bowl, whisk together the milk and flour. Pour into a saucepan and continuously stir on medium heat (don’t go away) until it starts to thicken. This is one of the methods for making white sauce but without having to add butter (the other method, making a roux, requires that you cook the butter and flour, then add the milk). When the milk thickens, add the cheese, and continue to stir until all cheese has melted. Pour the milk and cheese mixture on top of the pasta and cauliflower. Mix well.Bake at 350 for 10 minutes. If you like, broil for 5 minutes or until the top layer has a golden crust.
Prepare in advance. You just need to reheat for 10 mins before you eat it. Don’t forget to cover it when you reheat it in the oven.