Peel the potatoes, place them in a saucepan with some salt, pour boiling water on to them and cook them for about 25 minutes, or until tender.
Then drain them, add 75g of butter and the soured cream, start to mash them with a fork and finish off by whipping them to a purée with an electric mixer. Now add the cheese, taste and season. Next butter a shallow ovenproof oval 21cm baking dish, arrange the potato mixture in the dish and, with the back of a tablespoon, make 4 evenly spaced depressions.
Now break an egg carefully into each depression, place the dish in the oven and bake for 15 minutes, or until the eggs are just set. Serve sprinkled with chopped chives or spring onion tops.