First, prepare the bacon, boil the green beans until soft (if using fresh instead of canned) and slice the onion.
While the bacon cooks and the green beans boil, combine apple cider vinegar and sugar in a sauce pan on the stove and simmer for 10 minutes, stirring often, until the sugar dissolves.
Preheat your oven to 350℉.
Layer half of the green beans in the bottom of a rectangular casserole dish, then sprinkle over half of the bacon pieces, then half of the onion slices.
Repeat the layering process with the remaining ingredients, then top with silvered almonds.
Pour the apple cider vinegar and sugar mixture evenly overtop of the casserole.
Bake uncovered for 45 minutes.
Serve warm!
