Serves 3-4; can be multiplied.
Ingredients
4 cups leftover mashed potatoes
1 cup vegetable stock or water
1/2 tsp kosher salt
1/4 tsp fresh black pepper
Pinch of cayenne pepper (optional)
2 Tbsp plain nonfat Greek yogurt
1-1/2 cups grated mild Cheddar cheese + extra for garnish
Directions
In a small Dutch oven or heavy soup pot, add the mashed potatoes, stock, salt and pepper (and optional cayenne). Cook over low heat until the potatoes and stock have come together; you might have to nudge them with a whisk or wooden spoon every now and then.
If you like your soup super-smooth, remove the pot from heat, and use an immersion blender at this point to purée the soup.
Add the yogurt and 1-1/2 cups grated cheese. Gently stir until the cheese melts, and the soup turns a pale orange. Taste, and add more salt and pepper if needed.
Ladle into individual serving bowls, and top with a sprinkling of black pepper and a bit more cheese.
Serve hot.