In a large pot, melt the butter at medium heat.

Once melted, toss in the leek and leave it in over low heat, stirring occasionally over a period of 15 minutes.

Pour in the vegetable broth and stir in corn starch. Increase the fire to a high heat until the mixture boils.

Add in the potatoes and cooking cream. Once it has started boiling, lower heat and simmer for 30 minutes.

Add salt and pepper to taste. Turn of heat and serve. :)