In a large pot, melt the butter over medium heat and sauté the onion and garlic until soft.

Add the diced potatoes and broth. Bring to a boil, then reduce heat and simmer until the potatoes are tender, about 15-20 minutes.

Use an immersion blender to puree the soup until smooth, or transfer to a blender to puree in batches.

Stir in the heavy cream and season with salt and pepper.

Serve hot, garnished with fresh dill.