Whisk marinade ingredients together in a shallow bowl. Add chicken and marinate for at least 15 minutes.
Meanwhile, cook the penne pasta according to package directions and drain.
Turn grill to medium heat. Place the chicken on the hot grill, cover with grill lid and cook for a few minutes or until brown on bottom side.
Flip chicken, cover and cook until cooked through. Remove to a plate to rest.
Melt butter in a large skillet over medium high heat.
Add the onion and cook for 3-4 minutes until tender.
Add the garlic and cook for 30 seconds. Add flour and stir well.
Add chicken broth and milk and whisk until smooth.
Add cream cheese and stir until melted. Season with salt and pepper.
Add cooked pasta, tomatoes and parsley to the sauce and toss to coat.
Add grilled chicken on top. Sprinkle with freshly grated parmesan cheese, if desired.
