Melt the butter in a large, heavy pot or Dutch oven over medium-high heat. Add the ramps and season with salt and pepper. Cook, stirring, until the ramps are soft, about 6 minutes. Add the bay leaf and garlic, and cook, stirring, for 2 minutes. Add the stock and the potatoes and bring to a boil. Reduce the heat to medium and simmer, uncovered, until the potatoes are tender, and the mixture is thick and creamy, about 1 hour. Remove the soup from the heat. Discard the bay leaf and slowly add the cream, and stir to blend. Adjust seasoning.
Brush each side of the bread with the truffle oil. Place a slice of cheese on 4 slices of the bread. Place the remaining bread on top of the cheese. Put the sandwiches on a hot grill and grill until golden brown and the cheese melts, about 2 minutes on each side. Cut each sandwich into five finger-size slices. Serve with the soup.
Makes 10 servings