With just these few ingredients, it's surprising how delicious this recipe turns out to be! The brown sugar has a lot to do with that, but the vanilla doesn't hurt, either.
I usually toss the apple slices with lemon juice before serving just to make sure they don't brown while they sit out. It doesn't take long and the added flavor is actually pretty nice, too.
If you refrigerate any leftover dip it will harden. To serve again, just remove the dip from the refrigerator and let it reach room temperature, then mash together and stir to soften slightly.