Preheat the oven to 350 degrees. Grease a small dish. Slice the apple thinly and toss with the apple cider vinegar and vanilla. Line the small, greased dish with the apple slices, fanning them out evenly. Top the apples with the chopped butter, sprinkle with the cinnamon and brown sugar and sliced almonds. Bake for 20-25 minutes until the apples are tender. Serve alone or with a scoop of vanilla ice cream. Enjoy!