Preheat the oven to 350℉. Spray a 9x12-inch baking pan with nonstick spray (or rub with butter).
PREPARE THE DUMPLINGS:
Peel each apple, remove the cores and cut each apple into 8 wedges.
Separate the crescent dough into triangles. Starting at the wide edge, roll an apple slice up into the crescent dough. Set in the prepared pan. Repeat with the remaining apples and dough.
PREPARE THE SAUCE:
In a small saucepan over medium heat, melt the butter and stir in the brown sugar, cinnamon, vanilla and salt. Keep stirring until the butter is melted and the sugar dissolves a bit. Pour the sauce evenly over the dumplings.
Pour the soda around the edge of the pan (don't pour it directly on top of the dumplings).
BAKE AND SERVE:
Bake the dumplings for 30 to 35 minutes, until they have turned golden brown and the sauce is bubbling.
Serve two dumplings per person with a scoop of vanilla ice cream on top, if desired.