In a large pot or Dutch oven, melt butter over medium heat. Add chopped onion and cook until softened, about 3-5 minutes, then stir in minced garlic and cook for another minute until fragrant.

Whisk in the flour and cook for 1 minute, creating a roux. Gradually pour in the vegetable broth, stirring constantly to prevent lumps, then add the diced potato and bring to a simmer.

Cook for 10-12 minutes, or until potatoes are tender. Stir in the corn kernels, milk, and heavy cream; heat through for 5 minutes, but do not boil.

Season with salt and pepper to taste. For a creamier texture, you can blend about half of the chowder with an immersion blender or in batches in a regular blender, then return to the pot.

Ladle the hot chowder into bowls and garnish with fresh chopped chives before serving.