I love soups so as soon as the weather goes colder I have them at least one meal a day.
2 tbsp butter
2 medium/large potatoes, peeled and diced
2 leeks, cleaned and sliced
2 pts stock (I use chicken and add a little bit of cooked chicken to the soup too but vegetable stock is fine)
Salt and pepper to taste
Cream for serving (optional)
Saute the veggies in the butter gently for a few minutes. Then add the stock and simmer until they are all cooked through. Season to taste and puree before serving with a swirl of cream.