Nobody will know there is cauliflower in these potatoes unless you tell them.
You will need potatoes, milk, butter, salt, pepper and about 1 cup of pureed cauliflower. To puree my veggies I just steam them till soft and blend them with food processor or a blender till creamy. Sometimes you may need to add a bit of water.
Peel and cube the potatoes and boil till tinder.
Drain off water and add milk, butter, salt, pepper and the puree.
blend with a mixer till smooth and creamy. Add as much milk, butter, salt and pepper as you like.