Preheat oven to 350°F. Peel, core and slice each apple into 8 equal slices. In a small bowl, combine ¼ cup brown sugar and ¼ teaspoon cinnamon.
Split each biscuit horizontally into two layers. Flatten out each piece of biscuit until it's big enough to hold an apple slice (about palm size). Place an apple slice in the middle of the dough and sprinkle lightly with some of the brown sugar-cinnamon mixture (you won’t use all of it). Fold the dough up and over the apple slice. Pinch the edges of the dough closed to completely cover the apple slice. Place the wrapped apples, seam side down, in a 9x13 baking dish. Repeat with the remaining apple slices. You should have 16 total.
SAUCE: In a medium saucepan, combine water, ½ cup brown sugar, maple syrup, butter, and salt. Bring to a boil over medium heat and boil for 2 minutes, whisking occasionally. Remove from the heat and stir in the vanilla extract. Pour the liquid evenly over the apple dumplings.
Bake for 30-40 minutes, until the sauce is bubbling, the apples are tender, and the dumplings are puffed and golden brown. Allow to cool slightly (some of the sauce will get absorbed). Serve warm, spooning extra sauce over the dumplings.
Serving: These Apple Dumplings are best shortly after baking. Optional: top the dumplings with a scoop of vanilla ice cream or whipped cream. Storage: Store leftovers tightly covered in the refrigerator for up to 2 days. The longer the dumplings sit the more sauce they will absorb.