Cut 6 of the bacon slices into ½-inch pieces.
In a large skillet, over medium-high heat, cook, stirring often, until crispy; about 8 minutes.
Transfer to a plate lined with paper towels to drain; reserve drippings in skillet.
Once cooled, crumble cooked bacon; set aside.
Add onion to skillet; cook, stirring occasionally, until just tender; about 3 minutes.
Stir in green beans; cook, stirring often; 2 minutes.
Transfer green bean mixture to a 5-quart crock pot.
Stir in broth, salt, pepper, thyme sprigs and 2 uncooked bacon slices.
Cover and cook on high until beans are tender; about 3 hours.
Discard bacon and thyme; top with crumbled cooked bacon.
