The biggest problem is the unevenness of chicken breast. Some people try to even it out by pounding the chicken, but it is not the best method when you are wanting to chop it to use in a recipe, especially a casserole where it will be cooked even longer.
Dry, chewy chicken is the worst and there's nothing to cover it up once that happens.
Here's how to pre-cook the perfect chicken breast to chop up for recipes.
Heat the oven to 400 degrees.
Usually you will purchase chicken breast pieces that include the breast attached to the tenderloin. The tenderloin is smaller and thinner. Take a sharp knife and cut all the way through the meat along the white tendon line, removing the breast from the tenderloin.
Hold the breast upright with the thickest side on the cutting board. Cut the breast into two pieces, slicing through the entire middle (halving the thickness) so you will have two “breasts”, but half as thick. These two pieces will end up being close to the thickness of the tenderloin. Repeat for additional pieces.
Get a glass dish the proper size to just fit all the chicken pieces in one layer on the bottom. Spray the dish with cooking spray, and put the chicken in. Add 1/4 inch of water to the dish. Cover the dish with aluminum foil tightly.
Bake chicken for 30 minutes. Remove from oven, leaving the foil on. Let the chicken sit for 20 minutes. Chop.
Be sure and use the “water”, which is now “chicken broth” in your recipe if you can! Or, make the chicken a day early and store it in the broth in the fridge so it won’t dry out.