Cooking for kids: Broccoli and Stilton Soup

This is my daughters favourite homemade soup and goes by the name of "Green Gloop" in honour of the drink invented by Great Aunt Loretta in the BBC's childrens series "Grandpa In My Pocket". Unlike Aunt Loretta Green Gloop however this soup is really good.

1 onion, peeled and chopped
a little oil
1 large head broccoli (about 500g)
2 large potatoes, peeled and cubed
1/2 pint milk
75 g cheddar cheese, grated (Mature cheese preferably)
75 g Stilton, crumbled

Separate the broccoli into florets, cut the dry end off the stem but chop the remainder.
Sauté the onion in the oil until transparent. Add the potatoes and broccoli and stir until coated with the oil. Allow to cook for a few minutes.
Add enough water or fresh stock to come three quarters of the way up the vegetables. Put on the lid and leave to cook until the broccoli and potatoes are just soft when tested with a knife (about 10 minutes).
If possible, allow to cool a little then push through a sieve or liquidise until smooth.
Add enough milk give the consistency desired.
Put back on the heat and gently bring to the boil, add the cheeses and turn off the heat immediately. Allow the heat of the pan to melt the cheese whilst you stir. Do not allow to boil as this will cause it to separate.
Serve with crusty bread.