Cut turkey slices into matchstick-size strips; set aside. Core and thinly slice apples; set aside.
Melt butter in a wide skillet over medium-high heat. Add apples, turkey strips, and minced thyme; cook, stirring often, until apples are crisp-tender, about 3 to 5 minutes. Remove from pan and set aside.
Add cider (or apple juice) to skillet; boil, uncovered, until reduced by half (about 12 minutes). Add cream; boil, stirring often, until reduced by about a third (about 7 minutes).
Meanwhile, cook fettucine according to package directions until al dente (3 to 4 minutes for fresh, 7 to 9 minutes for dry). Drain; place in a warm bowl. Add cider sauce, apples, and turkey; toss well. Serve on warm plates; garnish each with a thyme sprig.
Makes 4 servings.