Preheat oven to 400 degrees and spray a 9x13 casserole dish with cooking spray.
Heat 2 tablespoons of the butter over medium high heat in a stock pot. Add the zucchini and onion and cook until liquid is evaporated and vegetables are just starting to brown, stirring occasionally.
Add the chicken, lemon juice, chicken broth, parsley, tomatoes, capers, garlic powder, salt and pepper. Stir to combine and cook for about 5 minutes until simmering. Stir in the cream cheese and continue to simmer until melted into the mixture.
Meanwhile, boil water and cook the pasta according to package directions. Once pasta is done, add about 1 ladle of the pasta water to the chicken piccata mixture simmering on the stove. Drain the pasta and add the pasta and 1/2 cup of the Parmesan cheese to the chicken and caper mixture. Stir well to combine and allow to simmer for about 5 more minutes.
Melt the remaining 2 tablespoons of butter and toss it with the stuffing mix (or croutons).
Pour the pasta mixture into the prepared baking dish.
Top with the remaining 1/2 cup of Parmesan cheese and the butter coated stuffing mix.
Bake for about 20 minutes until casserole is nice and bubbly and top is beginning to brown.