In a large saucepan cook onion, bacon, and garlic about 5 minutes or until onion is tender. Stir in beans; cook 1 minute more. Stir in tomatoes, chicken broth, dried thyme, and black pepper. Bring to boiling; reduce heat. Cover and simmer for 20 minutes.
Remove from heat. Mash bean mixture slightly with the back of a wooden spoon. Stir in spinach. Let stand, covered, for 1 minute to wilt spinach.
If desired, serve with toasted baguette slices and/or garnish with fresh thyme sprigs.