Heat olive oil in a medium pot or dutch oven over medium high heat. Add onions and sauté 5 minutes. Add zucchini and garlic and sauté 4 more minutes. Add broth, beans, orzo, tomatoes and oregano and bring to a boil. Reduce to a simmer and cook 14 to 18 minutes or until orzo is cooked and vegetables are tender.

Preheat oven to a low broil.  Place sliced bread on a large sheet pan. Sprinkle 1 tablespoon cheese on each slice of bread and broil on low until cheese is bubbly and bread is lightly browned.

To serve, ladle soup into 4 bowls and top each with 1 tablespoon pesto. Serve with cheese bread.