Peel a couple of pounds of Yukon gold potatoes and boil them until tender, about 15 minutes.
Drain and mash with a few cubes of butter.
Add in some sour cream, horseradish and grated cheddar. I used horseradish cheddar for extra flavour, but regular aged cheddar is fine too.
Mix it all together and fold in some chopped chives.
Serve with beef and Brussels sprouts.