In a medium-size saucepan, bring the corn cobs and the cream to a simmer. Remove from the heat, cover and steep for 30 minutes then discard the cobs.
While the cream is steeping, place the potatoes in a large saucepan and cover with water. Add the garlic and a large pinch of salt. Bring to a boil and cook over medium-high heat until the potatoes are tender, about 20 minutes.