Start by patting the chicken breasts dry with paper towels. Using a sharp knife, cut a pocket into the thickest part of each chicken breast, being careful not to cut all the way through to the other side. Season both the inside and outside of the chicken with salt, pepper, and dried thyme to ensure the flavor is well distributed.
In a small bowl, combine the chopped spinach, dried cranberries, and minced garlic. Toss them together so the garlic is evenly distributed. This mixture will provide the vibrant Christmas colors and the sweet and savory flavor profile that makes this dish so unique.
Stuff each chicken breast pocket with a generous amount of the spinach and cranberry mixture, followed by two strips of brie cheese. Press the edges of the chicken together and secure the opening with two or three toothpicks. This helps keep the melting cheese inside the chicken rather than letting it all run out into the pan.
Heat the olive oil in a large oven safe skillet over medium high heat. Once the oil is shimmering, add the chicken breasts to the pan. Sear them for about 3 to 4 minutes on each side until they are golden brown. This step is crucial for locking in the juices and giving the chicken a beautiful color for your holiday table.
Pour the chicken broth and apple cider vinegar into the skillet around the chicken. This creates a light steam and a simple pan sauce. Transfer the skillet to an oven preheated to 375 degrees Fahrenheit. Bake for 12 to 15 minutes, or until the internal temperature of the chicken reaches 165 degrees Fahrenheit.
