In a large bowl, add the cauliflower and spread it into an even layer.
Top with the lettuce.
Carefully spread the mayonnaise over the top, making sure to cover all the way to the edges of the bowl.
Sprinkle with the sugar, then layer on the onion, bacon, and Parmesan cheese.
Do not stir.
Cover and refrigerate overnight.
Just before serving, gently mix everything together and season with salt and pepper to taste.