Irish Potato Soup

INGREDIENTS

• 1/2 cup unsalted butter
• 1 medium onion, thinly sliced
• 3 leeks, sliced
• 3 large baking potatoes, peeled and cut into 1/4-inch-thick slices
• 3 (14 1/2-ounce) cans chicken broth
• 1 teaspoon salt
• 1/4 teaspoon pepper
• Toppings: shredded Cheddar cheese, crumbled cooked bacon, chopped fresh chives