Heat the olive oil or butter in a large pot over medium heat.
Sauté the chopped onion until translucent, about 5 minutes.
Add minced garlic and sauté for an additional minute until fragrant.
Stir in the diced potatoes and pour in the broth.
Bring the mixture to a boil, then reduce heat to a simmer.
Simmer until the potatoes are fork-tender, about 15-20 minutes.
Use an immersion blender to puree the soup until smooth.
Stir in the heavy cream and heat through, adjusting seasoning as needed.
Serve hot, garnished with chopped chives or green onions.
