For the grilled cheese: Slice the brioche into 4-inch slices. Butter one side of each piece of bread. Place in a large saute pan on medium heat, buttered-side down. Top each piece of bread with 1 slice American cheese. Mix the gruyere, provolone and Swiss together, and then evenly distribute the grated cheese mixture on top of the American. Drizzle with the truffle oil. Cook until the buttered side of the bread is toasted and golden brown. Sandwich the bread together and serve with the soup.
Working in four separate batches, add 3 cups of the tomato mixture and 1 cup cream to be blended and pureed until smooth. Repeat three more times. Then season with salt and pepper.
Add the rice and stir to coat with butter. Add the tomatoes and vegetable stock and bring to a boil. Turn the temperature down to low and let simmer until the rice is tender, 20 to 25 minutes. Remove from the heat.
For the bisque: In a large pot over medium heat, add the butter, garlic and onions. Cook until the vegetables begin to sweat, stirring constantly to avoid burning, about 5 minutes.
