Place the potatoes in a large pot with enough water to cover. Bring to a boil, and cook 15 minutes, or until tender.
Heat the olive oil in a skillet over medium heat, and cook the onion and garlic until tender.
Drain potatoes, and return to the pot. Pour in the cream, and mix in the onion, garlic, and dill. Bring to a boil, reduce heat to low, and simmer 20 minutes, stirring occasionally, until thickened. Season with salt and pepper.