Melt butter in a pot, sauté diced onion for 3 minutes until translucent.
Add diced potato, sweet corn kernels, vegetable broth, salt, and pepper.
Simmer for 15 minutes until potatoes are soft.
Blend half the soup using an immersion blender to thicken, then return to pot.
Stir in heavy cream, warm through for 2 minutes, and serve.