My step-father always makes such a big deal on Christmas Eve with the potato puree – he is the appointed cook every year and normally starts the preparations hours before dinner – when we were all kids we were nearly more excited with the final result (a fluffy mountain of steaming hot, pale yellow cream with a delicious velvety texture) than later on awaiting Santa Claus!

This is the basic recipe, and some tips on how to get the right consistency. You can flavour it with grated parmesan cheese, or nutmeg, or a good spoon of sweet mustard, or half tablespoon of grated cinnamon, … Otherwise you could use your fantasy and replace some of/all the milk with cream or yoghurt, … Or again, if it pleases you and your guests, you could add mushrooms or roast onions or parsnip, …

What you need (for 2 people):

4 medium-big potatoes (approx 200 gr.)
1 slug of milk
butter
olive oil
salt

How you do it:

According to the traditional recipe, you should boil the potatoes with their skin and peel them only after they are cooked. However, more modern theories recommend to steam the potatoes peeled and cut in medium chunks, or again to bake them or cook them in the microwave, the point being that you are trying to avoid as much as possible that your potatoes absorb liquid to give you – horror horror – a watery puree.
Once the potatoes are cooked (and peeled), mash them to a pulp, using a masher or a fork. There is really no need to inconvenience yourself with a food processor, as the potatoes at this point should be tender and sufficiently soft to 'melt' under your masher. Add butter, a little oil and a slug of milk and start stirring the mix on a low heat. You can continue to add milk until you reach your preferred consistency.
The real secret here is to do everything while the potatoes are steaming hot, otherwise you risk that the ingredients don't blend or that – revulsion revulsion – you leave lumps in!