In a medium bowl, place the dry baking mix. Add just enough of the cider mixture from the slow cooker—about 1/2 to 3/4 cup—to form a soft, spoonable dough. Stir gently until no dry pockets remain, but do not overmix; the dough should be thick and slightly sticky.
Turn the slow cooker to HIGH. Once the cider mixture is hot and beginning to steam around the edges (this usually takes about 15–20 minutes), drop spoonfuls of the dumpling dough directly into the hot liquid, leaving a little space between each one. They will puff and expand as they cook.
Cover the slow cooker with the lid, keeping it closed to trap the steam. Cook on HIGH for about 1 1/2 to 2 hours, or until the dumplings are puffed, set in the center, and no longer doughy when you gently cut one open. The syrup will thicken slightly as it cooks.
Once the dumplings are done, turn the slow cooker to WARM. Let them rest for about 5–10 minutes so the sauce can settle and cling to the dumplings a bit more.
