Place ham hock and water or stock into a slow cooker. Cook for 4 hours on low.
Add the diced vegetables and cook on low for a further 4 hours.
Remove the skin, gristle and bones.
Cut the corn off the cob and add to the broth.
Turn the slow cooker to high. Melt the butter in a microwave jug for approximately 30 seconds.
Add the flour, then microwave for another 10 seconds. Slowly mix in the milk, then stir into the broth to thicken.
Cook for a further 20 minutes.
