We had our work christmas party here last year:
Guillaume at Bennelong - Sydney Opera House, Australia
OMG the mash was fantastic! I saw the chef from here on TV and this is what he does:
1. boil potatoes with the skin on
2. when cooked, peel the potatoes and push the potatoes threw a sieve.
3. boil milk in one saucepan
4. put another pot onto the stove on low heat and put the potato in and stir
5. pour in the milk mixture and cold (salted) butter while stirring furiously.
6. serve
What point 5 does is blend the butter and milk with the potato, but also reduce the amount of liquid in it.
edit: I found a video of this - it is a beef bourguignon with mash - the mash starts at about 2:30.
http://www.sbs.com.au/food/foodsafar...ef_bourguignon
This is basically what I do at home (though I peel my potatoes and just use a masher rather than a sieve), and I just add the butter and cream (or usually full cream milk) straight into the pot, then stir.
It will come out really creamy and not sloppy at all