In a large bowl, toss the potatoes with 1/4 cup olive oil, garlic, salt, and pepper. Spread on a baking sheet and roast for 30 minutes, until cooked through.
Saute the onions and fennel with 2 tablespoons olive oil in a large stockpot on medium heat until translucent, 10 to 15 minutes. Add the roasted potatoes (including the scrapings from the pan) and the chicken stock. Cover and bring to a boil. Lower the heat and simmer uncovered for 1 hour, until all of the vegetables are very soft. Add the heavy cream and allow the soup to cool slightly. Pass the soup through the largest disk of a food mill or chop coarsely in batches in a food processor fitted with a metal blade. Taste for salt and pepper. Reheat and serve hot.
Ina used Yukon Gold instead of red potatoes when taping this episode and garnished the soup with fennel fronds and a drizzle of heavy cream.
This recipe has been updated and may differ from what was originally published or broadcast.