In a large Dutch oven, heat the olive oil over medium heat. Add the onion, carrot, salt, pepper, and fennel seeds, if using. Cook, stirring occasionally, until the vegetables are slightly softened, 5 to 7 minutes. Add the cabbage and garlic to the pot and stir to combine. Cook, stirring occasionally, until the cabbage is slightly softened, about 5 minutes.
Add the broth, tomatoes, and bay leaves. Bring to a simmer; cover, and cook until the cabbage is tender, about 15 minutes. Stir in the white beans and simmer, uncovered, for 5 minutes. Remove the bay leaves.