Preheat the oven to 375 degrees. Coat a 9"x13" pan with cooking spray.
In a large bowl, stir together the chicken, ricotta cheese, 1/2 cup mozzarella cheese, 1/4 cup parmesan cheese, Italian seasoning and salt and pepper to taste.
Melt the butter in a large pan over medium heat. Whisk in the flour and cook for 1 minute.
Pour in the milk and cream, then simmer, whisking constantly, until sauce has just thickened.
Add the remaining 3/4 cup parmesan cheese to the milk mixture, along with salt and pepper to taste.
Stir until cheese has melted.
Spread 1/3 of the sauce into the bottom of the prepared pan.
Spoon the chicken filling into the jumbo shells, and arrange the shells in a single layer in the pan.
Spoon the remaining sauce over the top and sprinkle with 1 cup mozzarella cheese.
Bake, uncovered, for 25 minutes or until pasta is bubbly and cheese has just started to brown.
Sprinkle the bacon, tomatoes and parsley over the top, then serve.