Preheat oven to 350 degree F. Cut apples in half lengthwise and cut out the core to make a deep well. Sprinkle cut side of apples with 1 teaspoon of the thyme. Place apple halves, cut side down in a 2-quart rectangular baking dish. Pour apple cider over apples in baking dish. Bake, covered, 25 minutes.
Meanwhile, combine the raisins, feta cheese, and remaining thyme. Toss mixture with olive oil.
Remove apples from oven and turn them cut side up. Spoon apple cider in bottom of dish over apples. Spoon mixture into centers of apples halves; mound filling as needed. Bake apples, uncovered, about 5 minutes more or until the filling is just heated through.
Transfer apple halves to serving platter. Strain juices through a strainer lined with 100-percent-cotton cheesecloth, if desired. Measure juices. If necessary, add enough apple cider to make 3/4 cup. Bring to boiling in a small saucepan over high heat. Continue boiling about 10 minutes or until mixture is reduced to 1/4 cup and slightly thickened. Spoon over apple halves to serve. Makes 6 servings.