Combine 1 can of Cannellini beans and 1 cup of broth in a blender; blend until completely smooth. Set aside.
Heat oil in a large stockpot or Dutch oven over medium. Add onions and carrots; cook until softened, stirring occasionally, about 6 or 7 minutes. Add garlic, salt, and pepper; cook 2 minutes. Add remaining can of Cannellini beans, chickpeas, and rosemary; stir to combine, and cook for 1 minute.
Stir in blended bean and broth mixture, remaining 3 cups broth, and chopped escarole. Bring mixture to a boil; reduce to a simmer and cook, uncovered, 20 to 25 minutes, or until soup slightly thickens. Stir in lemon zest and juice. Gradually sprinkle in Parmesan cheese, stirring continuously (don't add it all at once or it may clump).
Ladle soup into each of 6 bowls, and garnish with additional Parmesan cheese, cracked black pepper, and chopped rosemary, if desired. Serve with crusty bread.