Heat olive oil in an 8-quart stockpot. Add potatoes and onions. Cook for about 5 minutes. Add garlic and cook about a minutes, stirring.
Add all remaining ingredients. Cover pot and cook on medium/low heat for about 30 minutes. Check veggies and cook a few minutes more if needed.
Heat oven to 400 degrees. Lay 4 slices of bread in a bread pan. Layer cheese slices over 2 slices of bread. Toast the bread for 8-10 minutes or until lightly browned. Sandwich together and cut each sandwich into 12 croutons.
Top the soup with grilled cheese croutons and fresh or dried parsley.