This hearty soup can be made ahead and frozen for up to three months, so you can enjoy it well into spring.
In a bowl, combine turkey, garlic, egg, breadcrumbs, cheese, 1 teaspoon salt, and 1/4 teaspoon pepper. Roll mixture into 1-tablespoon balls.
In a large pot, heat oil over medium. Add onion and cook, stirring occasionally, until softened, 3 to 4 minutes. Add broth and tomatoes with juices; bring to a simmer. Add meatballs and cook, without stirring, until they float to surface, about 5 minutes.
Add as much escarole to pot as will fit. Cook, gradually adding remaining escarole, until wilted and meatballs are cooked through, about 5 minutes more. Thin soup with water, if desired; season with salt and pepper. Serve, sprinkled with cheese.