Combine ½ cup beans, ½ cup tomatoes, reserved tomato juice and chicken broth in the bowl of a food processor; purée until smooth, about 30 seconds.
Heat oil over medium heat in a Dutch oven until shimmering. Add sausages and brown on all sides, about 8 minutes; transfer to a plate and set aside.
Add onion to fat left in pot and cook until softened, about 5 minutes. Stir in garlic, Italian seasoning and pepper flakes and cook until fragrant, about 30 seconds.
Stir in puréed bean mixture and cook 1 minute, scraping up any browned bits. Stir in kale, remaining tomatoes, and ¼ teaspoon salt. Bring to a simmer then reduce heat to medium-low, cover, and cook, stirring occasionally, until kale is wilted and tender, about 15 minutes.
Stir in remaining beans and nestle sausages into pot; adding any accumulated juices.
Cover and cook until sauce is slightly thickened and sausages are heated through, about 10 minutes. Season with salt and pepper and serve.