Place the bacon in a large skillet and cook over medium-high heat, turning occasionally, until evenly browned, about 10 minutes.
Remove bacon with a slotted spoon to a plate lined with paper towel.
Drain and discard liquid from 1 can of green beans; empty both cans into a saucepan over low heat. Bring to a simmer; add bacon and sweet onion.
Increase heat to medium-low. Stir cinnamon, salt, and nutmeg into the green beans. Cook the mixture until the onions are transparent but not yet soft, about 10 minutes.
