In a bowl, combine plain Greek Yogurt, cream cheese, shredded cheese, seasonings, and spinach. Set it aside and chill in the fridge until ready to stuff the chicken breasts.
Slice the boneless chicken breasts in half. Place one sheet of saran wrap on top of a cutting board. Place the sliced chicken breasts on top, cover with another sheet of saran wrap then gently pound each slice with a meat mallet(click: refer to this one). Lay out one slice of boneless chicken breast into parchment paper. Spread stuffing on top.
Gently roll up the chicken then dread with the bread crumbs. Repeat with the remaining chicken breasts.
Preheat the oven to 375°. Place the stuffed chicken in the Spray oil spray on a foil-lined sheet pan. Secure each stuffed chicken breast with toothpicks.
Bake the stuffed chicken for 35-40minutes or until the internal temperature is 165°