Ingredients

• 2 leeks, finely chopped (white part only)
• 1 clove garlic, finely chopped
• 4 medium potatoes (red or Yukon Gold), chopped
• 2 tablespoons butter, divided
• 1 tablespoon olive oil
• 1 1/2 teaspoons ground mustard
• 2 tablespoons flour
• 1/2 cup water
• 3 cups chicken broth
• salt, pepper, and celery salt, to taste
• 1/2 cup shredded Cheddar cheese
• 2 tablespoons Parmesan cheese
• 1 cup milk
• 3 ounces chopped portobello mushrooms
• croutons for garnish, if desired