Toast 1 teaspoon fennel seeds in a skillet with 1 tablespoon olive oil for 1 minute. Add 1 head thinly sliced red cabbage in batches, season with salt and pepper and stir until wilted. Add a pinch of sugar and a splash each of red wine vinegar and chicken broth. Partially cover and simmer over medium-low heat, stirring occasionally, until the cabbage is soft, about 30 minutes. Toss with 2 tablespoons butter and a handful of chopped parsley.