Wash your head of Cauliflower and place on a cutting board upside down. Insert a sharp knife in the center and cut out the stem. This will let you cut the florets easily with no crumbs.

In a pre heater medium high heat pan, add some oil, and place the florets. Cook then on the medium high heat until they get charred. You shouldn't cook them through so the heat has to be high-ish. Turn the sides so it gets a descent char all around. When you're done set aside in a bowl. The cauliflower should be still hard in the middle.

In the pan add some oil and sautee the onions and garlic with a pinch of salt, until translucent.

Then add the pepper and paprika.

Add the cream, bechamel, mustard and water, stir, cover and let simmer on a low heat.

After 5 minutes of simmering, switch off the heat and wait for a minute before adding a little bit of cheese to the mixture and mix.

TIP: cheese best incorporates in to liquids when the liquid is at 80c. By waiting, the mixture cools and you avoid the cheese getting clumpy and sticking to the pan or spatula.

After the 20 minutes dollop your cheese of choice on top of the mixture and sprinkle with parmesan.
I chose to add little amount of Raclette cheese but you can add mozzarella/provolone/cheddar or whichever you prefer and you can heap on the cheese if you don't mind the calories.
Place back to the oven for another 15 minutes.