Melt butter in a soup pot and sauté diced onion until translucent.
Add diced potatoes, sweet corn kernels, vegetable broth, salt, and black pepper.
Cover pot and simmer for 15 minutes until potatoes are soft.
Mash a few potato cubes against side of pot to thicken soup naturally.
Stir in heavy cream, warm through for 2 minutes, and serve hot.