Best Mac and Cheese with Sweet Potato - Thank you Nigella

Currently I am feeding a teenage boy...wow they have huge appetites so always thinking of tasty filling food
Also, mindful of the budget.
This Mac and Cheese... bulked up with pasta...also with an excellent addition of
Kumera (sweet potato)
Cheap and Cheerful and so so tasty.  Quite a different texture. Thumbs up from the Teenager

This recipe is from Nigella's Book “Simply Nigella”
I found it on my Epicurious Website and just had to share

2 large sweet potatoes peeled and cubed
2 cups macaroni, or other small, short pasta I used Farfalle
4 tablespoons unsalted butter, softened
3 tablespoons all-purpose flour
2 cups whole milk
1 teaspoon English or French mustard (works with both)
1/2 teaspoon paprika
3/4 cup feta cheese crumbled)
1 1/2 cups sharp Cheddar, grated
Sea Salt and pepper to taste
Preheat the oven to 200°C Put on a large-ish pan of water to boil,
with the lid on to make it come to a boil faster.

When the water’s boiling, add salt to taste, and then the sweet potato pieces, and
cook them for about 10 minutes or until they are soft.
Scoop them out of the water into a bowl–using a ”spider” or slotted spoon–
and lightly mash with a fork, without turning them into a purée.

Don’t get rid of this water, as you will need it to cook your pasta in later.

In another saucepan, gently melt the butter and add the flour,
whisking to form a roux, then take the pan off the heat,
slowly whisk in the milk and, when it’s all combined and smooth,
put back on the heat.
Exchange your whisk for a wooden spoon, and continue to stir
until your gently bubbling sauce has lost any floury taste and has thickened.
Add the mustard and ¼ teaspoon of the paprika.
Season to taste, but do remember that you will be adding Cheddar and salty feta later,
so "underdo" it for now.

Cook the pasta in the sweet-potato water, starting to check 2 minutes earlier than packet instructions dictate, as you want to make sure it doesn’t lose its bite entirely.
Drain (reserving some of the pasta cooking water first) and
then add the pasta to the mashed sweet potato, and
fold in to combine; the heat of the pasta will make the mash easier to mix in.

Add the feta cheese to the sweet potato and pasta mixture,
crumbling it in so that it is easier to disperse evenly,

then fold in the white sauce, adding 1 1/4 cups grated Cheddar as you go. 

Add some of the pasta cooking water, should you feel it needs loosening up at all.
It did

Check for seasoning again, then, when you’re happy, spoon the brightly sauced macaroni cheese into 4 small ovenproof dishes of approx. 1 1/2 to 1 3/4 cup capacity
(or 1 large rectangular dish measuring approx. 12x8x2 inches deep and 6 1/2 cup capacity).

Sprinkle the remaining Cheddar over each one,

Put the pots on a baking tray, pop into the oven and bake for 20 minutes
(or, if you’re making this in a larger dish, bake for 30–35 minutes), by which time they will be piping hot and bubbling, and begging you to eat them.

I made this earlier in the day then into the oven just before we wanted to eat...and also froze 2 of the containers
Always looking ahead