Heat olive oil in a large saucepan over medium-high heat until shimmering. Add onions, carrots, and celery and cook, stirring frequently, until softened but not browned, about 3 minutes. Add garlic and dried red pepper flakes and cook, stirring constantly until fragrant, about 1 minute. Add chicken broth, beans and their liquid, rosemary stems, parmesan rind, and bay leaves. Increase heat to high, and bring to a boil. Reduce to a bare simmer, add kale, cover and cook for 15 minutes.
