01 - Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper or apply a light coat of oil.
02 - In a small bowl, combine garlic powder, paprika, salt, and black pepper. Set aside.
03 - Pat chicken breasts dry with paper towels. Using a sharp knife, cut a deep pocket into each breast, taking care not to slice through.
04 - Rub each chicken breast with olive oil and the prepared seasoning mixture, ensuring to season inside the pockets as well.
05 - In a mixing bowl, combine finely chopped broccoli, shredded cheddar cheese, softened cream cheese, grated Parmesan, Dijon mustard, and minced garlic. Mix until well distributed.
06 - Fill each pocketed chicken breast with the broccoli-cheese mixture, securing the filling with toothpicks if necessary.
07 - Place the stuffed chicken breasts onto the prepared baking sheet.
08 - Bake in the preheated oven for 25 to 30 minutes, or until chicken is cooked through with an internal temperature of at least 165°F (74°C) and cheese mixture is bubbling.
09 - Allow chicken to rest for 5 minutes before serving. Remove any toothpicks prior to plating.