Heat large pot over medium heat. When pot is warm, add butter and let melt, swirling pot occasionally to distribute butter across surface.
When butter is melted but not yet browned or bubbling, add diced potatoes, chopped onions, and minced garlic. Stir to incorporate, then simmer vegetables 5 to 6 minutes or until onions are very soft and potatoes begin to soften. Stir vegetables occasionally to prevent sticking.
Once onions have softened, add chicken broth and 4 cups corn kernels (see Notes). Stir to incorporate, making sure to scrape up any bits of onion or garlic that may be stuck to bottom of pot.
Increase heat to medium-high and bring liquid to boil. Once liquid begins to boil, immediately reduce heat to medium-low and simmer, uncovered, 10 to 12 minutes or until potatoes and corn are tender.
When corn and potatoes are ready, carefully remove pot from heat and let mixture cool slightly. Insert immersion blender into pot and purée ingredients until mixture is completely smooth. See Notes below if using traditional blender.
When soup is smooth, add heavy cream and stir until fully incorporated.
Return pot to medium-low heat and stir in remaining 1 cup corn kernels and lime juice. Season with salt and pepper to taste. Simmer 5 minutes or until corn kernels are tender.
Divide soup into preferred portions. Top with chopped chives or cilantro if desired and serve warm with lime wedges (optional).