Melt the butter in a 6-quart stock pot over medium-high heat. Add the ramps. Season with salt and black pepper. Saute until the ramps are wilted and soft, about 6 minutes. Add the bay leaf and garlic, stirring for 2 minutes. Add the stock and potatoes and bring the mixture to a boil. Reduce the heat to medium and simmer, uncovered, until the potatoes are very soft and the mixture is thick and cream, about 1 hour. Remove the soup from the heat. Discard the bay leaf. Slowly add the cream. Stir to blend. Reseason the soup. Brush each side of the bread with the truffle oil. Place a piece of cheese on top of four slices of the bread. Place the remaining slices of bread on top of the cheese. Place the sandwiches on the hot griddle. Grill the sandwiches for 2 to 3 minutes on each side or until golden and the cheese has melted. Cut each sandwich into five finger-size slices. Serve the sandwiches with the soup.