Halve and core 2 crisp apples; trim the uncut sides to sit at. Scoop out and chop most of the flesh. Combine with 1/2 cup each shredded cheddar and crumbled cornbread, 1/4 cup each chopped celery and scallions, 2 tablespoons olive oil and 1 teaspoon chopped thyme; season with salt and pepper. Fill the apples with the stuffing; arrange in a baking dish. Pour in 1/2 cup apple cider. Cover with foil and bake at 425 degrees F until tender, 20 to 25 minutes. Uncover and bake until crisp, 10 minutes.