1. Combine first 4 ingredients in a saucepan; bring to a boil. Cook until reduced to 1/2 cup (about 32 minutes). Remove from heat; discard thyme and shallot. Stir in butter, mustard, 1/8 teaspoon salt, and 1/4 teaspoon pepper.
2. Preheat oven to 475°.
3. Sprinkle pork evenly with remaining 3/8 teaspoon salt and remaining 1/4 teaspoon pepper. Lightly coat with cooking spray. Place pork in a roasting pan; bake at 475° for 9 minutes. Turn pork over; brush evenly with 2 tablespoons cider mixture. Bake an additional 8 minutes or until thermometer inserted in the thickest portion of pork registers 140°. Let pork stand for 10 minutes. Slice pork, and serve with remaining sauce.