In a large pot, add 1-2 inches of water and bring to a boil. Add a steamer insert, make sure water level is below the insert and not touching the insert. Add the diced potatoes and fennel to the steamer and cover the pot. Steam for about 15 minutes.
Let the potatoes and fennel cool slightly and then transfer to a food processor. Add the cream, butter, salt and pepper. Pulse to combine and puree, be careful not to over mix.