Bring 2 inches of water to a boil in a medium saucepan. Place the chicken in a steamer basket over boiling water, cover, and cook for 10 minutes.
Flip the chicken over, sprinkle the pepper onto chicken, if using. Add the zucchini, apple and then the spianch on top of the chicken. Cover and cook for 10 additional minutes. Do not mix and keep spinach on top. Let slightly cool. Reserve steamer water.
Remove chicken to check for doneness and then roughly chop.
Transfer all ingredients into a blender or food processor. For stage 2 puree - blend for 1-2 mintues or until you achieve desired consistency, adding reserved water in 1/4 cup increments if needed. For stage 3 puree - pulse in 5 second intervals until you have achieved the desired chunky consistency, adding reserved water in 1/4 cup increments if needed.