1. Prepare the Turkey Breast: Preheat your oven to 375 F (190 C). Pat the turkey breast dry with paper towels. This helps achieve a better sear and crispier exterior. Rub the turkey breast all over with olive oil, then season generously with salt and black pepper.

2. Sear for Color: Heat an oven-safe skillet (like cast iron) over medium-high heat. Once hot, place the seasoned turkey breast in the skillet and sear for 3-4 minutes per side until golden brown. This step locks in juices and adds a rich depth of flavor.

3. Whisk the Glaze Ingredients: While the turkey is searing, in a small bowl, whisk together the apple cider, brown sugar, apple cider vinegar, and Dijon mustard until well combined.

4. Glaze and Roast: Pour the apple cider glaze over the seared turkey breast in the skillet. Transfer the skillet to the preheated oven. Roast for 45-60 minutes, or until an instant-read meat thermometer inserted into the thickest part of the turkey breast registers 165 F (74 C). Baste the turkey with the glaze every 15-20 minutes to build layers of flavor and keep it moist.

5. Rest the Turkey: Once the turkey reaches 165 F, remove the skillet from the oven. Carefully transfer the turkey breast to a cutting board and tent it loosely with aluminum foil. Let it rest for at least 10-15 minutes. This resting period is crucial for the juices to redistribute, ensuring a tender and moist turkey.

6. Thicken the Glaze (Optional): While the turkey rests, if you desire a thicker glaze, place the skillet back on the stovetop over medium heat. In a small cup, whisk together the cornstarch and cold water to create a slurry. Pour the slurry into the simmering glaze in the skillet, whisking constantly until the glaze thickens to your desired consistency, about 1-2 minutes.

7. Slice and Serve: Slice the rested turkey breast against the grain into thick pieces. Arrange on a serving platter and spoon the warm apple cider glaze generously over the top. Garnish with fresh chopped parsley, if using, for a pop of color.