Preheat the oven to 400°F (200°C). Lightly oil a baking dish or sheet pan.

Using a sharp knife, carefully cut a deep pocket into the thick side of each chicken breast. Cut approximately three-quarters of the way through without slicing completely through the chicken.

Pat the chicken breasts dry with paper towels. Rub them all over with olive oil, then season both the inside and outside with garlic powder, dried thyme, kosher salt, and black pepper.

Keep the Brie refrigerated until you are ready to stuff the chicken. Cold Brie is firmer and easier to slice and arrange inside the pockets.

Add some spinach to each pocket, followed by slices of Brie and dried cranberries. Finish with another small layer of spinach to help distribute the filling.

Gently close each chicken breast around the filling. Avoid overstuffing. Secure the openings with toothpicks if necessary.

Arrange the Cranberry Brie Stuffed Chicken in the prepared baking dish, leaving a little space between each piece. Bake for 25–30 minutes, or until lightly golden and the thickest part of the chicken reaches an internal temperature of 165°F (74°C).

For additional browning, broil the chicken for 1–2 minutes, watching it carefully to prevent burning.

Rest for 5–10 minutes before slicing. This allows the juices to settle and gives the creamy Brie filling time to thicken slightly.