Heat an air fryer to 375 degrees.

Carefully cut a pocket lengthwise down the side of the chicken breast, being careful not to cut all the way through.  This will create the pocket for the broccoli cheese filling. (If your chicken breasts are really thick, pound them out a little before cutting the pocket).

Using a fork, mash together the cream cheese, broccoli, and shredded cheddar cheese until well combined.

In a flat dish, mix together the whole wheat bread crumbs, panko, garlic salt, and onion powder. 

In a wide bowl, lightly beat the egg.

Stuff the broccoli cheese mixture into the pocket you cut in the chicken. Use toothpicks to secure if necessary.  Dip all sides of the stuffed chicken breast into the egg, then into the breadcrumb mixture.

Place the stuffed and breaded chicken breasts into the air fryer.  Cook for 10 minutes, then flip and cook for 7 more minutes, or until the chicken reaches an internal temp of 165 degrees.