Step 1 Heat the oil in a large pot over medium-high heat. Add the onion, carrots and celery. Cook, stirring occasionally, until softened, 5 minutes. Add the garlic and cook 1 minute. Add the tomatoes and chicken stock. Increase the heat to high and bring to a boil, then reduce the heat to low and simmer until the vegetables are tender, 15 minutes. Stir occasionally.
Step 2 Meanwhile, using a cookie cutter or scissors, cut the bread slices into ghost shapes. Cut the cheese slices into the same shape. Toast the ghosts in a toaster oven. Place them on an oven-safe tray, then place the cheese on top. Use 3 peppercorns to make eyes and a mouth for each ghost. Put them back into the toaster oven and toast again to melt the cheese. (If you don't have a toaster oven, you can broil the cheese toasts about 4 inches beneath the broiler element until the cheese is bubbly, 2 minutes.)
Step 3Puree the soup in a blender in two batches. Return it to the pot. Add the cream and adjust the seasoning with salt and pepper. Heat, then serve in bowls with the ghost toasts on top.