Puree all ingredients in processor. Season with salt and pepper. (Pesto can be made 1 day ahead. Cover and refrigerate.)
Combine first 4 ingredients in heavy large pot. Cover and cook over medium-low heat until vegetables are almost tender, stirring occasionally, about 8 minutes. Add broth; bring to boil. Stir in orzo; boil uncovered until orzo is almost tender, stirring often, about 12 minutes. Add green beans; reduce heat and simmer until beans are tender, about 6 minutes. Stir in cannellini and crushed pepper; simmer until heated through, about 3 minutes. Season with salt and pepper.
Divide pesto among 4 bowls. Ladle soup over pesto; swirl to blend. Sprinkle with 2 tablespoons cheese.