Pre-heat the oven to 375°F.
Lightly grease a baking dish or line with parchment paper.
Using a sharp knife, carefully cut a pocket into the side of each chicken breast without slicing all the way through.
While the chicken is baking, in a small saucepan, over low heat, whisk together honey, balsamic vinegar and Dijon mustard; sauté until slightly thickened; set the glaze aside.
In a medium bowl, mix the chopped spinach, dried cranberries and slices of brie cheese; thoroughly combine the ingredients.
Stuff each chicken breast with the mixture, securing the opening with toothpicks, if needed.
Rub the chicken breasts with olive oil and season with garlic powder, dried thyme, salt and black pepper.
Heat a large oven-safe skillet over medium-high heat.
Sear the chicken for 2 -3 minutes per side until golden brown.
Transfer the skillet to the pre-heated oven (or place the chicken in the prepared baking dish) and bake for 20 – 25 minutes or until the internal temperature of the chicken reaches 165°F.
Remove from the oven, remove the toothpicks, if using, and drizzle the glaze over the chicken before serving.
Garnish with additional dried cranberries or fresh spinach, if desired.
