Heat a large pot (not nonstick) over medium-high heat. Crumble in sausage. Cook, stirring, 5 minutes, until browned, breaking apart large pieces with a wooden spoon. Remove to a plate with a slotted spoon.
Reduce heat to medium. Add onion and carrots. Cook 5 minutes. Stir in garlic, red pepper flakes and escarole. Cook, stirring, 2 minutes.
Pour in chicken broth and bring to a simmer over high heat. Reduce heat to retain simmer; cook 20 minutes. Return sausage to pot along with drained beans. Heat through. Serve sprinkled with Parmesan, if desired.