In a medium bowl, combine cheeses, chopped artichoke hearts, sun dried tomatoes, mayonnaise and parsley. Mix well and set aside.
Cut each chicken breast horizontally (as if making a chicken breast cutlet) then gently pound them using a meat mallet. Season with generously with salt and pepper.
Over medium heat in a large skillet, brown chicken breast cutlets in butter. About 2-3 minutes per side, or until no longer pink inside. Working in batches as needed.
Remove all cooked chicken breast cutlets from the skillet and set aside on a plate.
Add sliced mushrooms and garlic to the skillet the chicken was cooked in, add a squeeze of fresh lemon juice and season with salt and pepper. Saute mushrooms for 2-3 minutes or until lightly cooked.
In an oven proof casserole dish transfer sauteed mushrooms and any leftover butter (or leave in the skillet). Layer cooked chicken cutlets and generously top each with the artichoke mixture.
Broil for 3-5 minutes to heat the topping and melt the cheese. Remove from the oven and allow to rest for about 5 minutes before serving. Then enjoy!