Preheat the oven to 350°. In a food processor, combine butter, cheddar, flour, and salt. Pulse until the mixture looks like coarse sand, about 1 minute.
One at a time, add 2 tablespoons cold water, pulsing until the dough clumps together, about 30 seconds. Remove it from the processor, wrap it in plastic, and refrigerate it for 20 minutes.
Roll out the dough onto parchment paper. With a knife, trace an overturned soup bowl to cut 6 circles (the dough will shrink to fit as it cooks). Cut a mouth, then add fangs and a triangular widow's peak. Cut eye holes (the bottom of a small pastry tip works well).
Place the faces on a parchment paper-lined cookie sheet. Insert black olive slices for the eyes. Bake them 15 to 18 minutes, until crispy and golden.
Meanwhile, heat 3 cans of tomato soup. Pour it into bowls and top each with a face. If desired, add slices of red bell pepper for eyebrows. Serve the soup immediately. Makes 6 servings.