Preheat oven to 425°.

Rinse and then pat dry the green beans and then cut the tips off of both ends. Place them in a rimmed sheet pan.

Cut the bacon into small pieces with kitchen shears and dice the onion, then add both to the green beans. 

Drizzle the olive oil over the beans, add the salt and pepper and then mix all together until everything is coated with the oil. 

Bake for 20-25 minutes until beans and bacon are browned.