In a medium bowl, combine chicken with ½ teaspoon salt, ½ teaspoon pepper, and 2 tablespoons of Ranch dressing mix.
Cook bacon and penne and set aside.
In a large skillet over medium high heat, melt 4 tablespoons butter and 1 tablespoon olive oil. Chop raw chicken into bite sized pieces also trimming off any unwanted pieces of fat. Add chicken to pan and put the lid on. Cook for about 3 min then check the inside of a chicken bite. Once finished, remove with a slotted spoon and set aside.
Reduce heat to medium. Saute onion in pan drippings until soft and translucent. Add garlic and saute for 1 more minute.
To the same pan (with the onion and garlic), add 4 tablespoons butter. When butter is melted, add flour, Italian seasoning, basil, remaining 1 teaspoon salt, and remaining 1 tablespoon Ranch dressing mix. Stir.
Using a whisk, gradually add chicken broth (½ cup at a time), stirring to combine well with the flour mixture. Add heavy cream. Add cream of chicken soup. Continue to stir, heating until bubbly. Add parmesan and stir until cheese is melted. Remove from heat.
To the sauce, add 8 slices chopped bacon, sun-dried tomatoes, chicken, and pasta. Combine.
Pour pasta mixture into a greased 9x13 pan. Sprinkle with the remaining 4 pieces of chopped bacon. Top with Italian cheese. Sprinkle with dried or fresh chopped parsley, if desired.
Bake uncovered at 350º for 30 minutes or until cheese is melted and edges are bubbly.