Preheat oven to 350°F. Spray a 2-quart casserole dish with nonstick spray.
Cook pasta according to package directions, but only cook it until it's al dente (you still want a little bite to it). Drain the pasta and set it aside.
Melt butter in a large, deep skillet over medium heat. Add mushrooms, onion, celery and bell peppers. Cook until the vegetables have softened, 4 to 5 minutes. In a medium bowl, mix milk and soup until smooth. Add this mixture to the vegetables in the pan. Stir in cheddar cheese. Continue to heat the mixture until the cheese has melted and the sauce is smooth. Add in chicken, pasta and tabasco, and season to taste with salt and pepper. Pour the mixture into the prepared casserole dish. Sprinkle Jack cheese on top.
Bake for 35 minutes, or until the casserole is hot and bubbly and golden brown.
Notes
*If you're trying to figure out a serving size for this casserole, simply use a knife to divide the pan into 6 equal servings. There's your serving size (it's pretty substantial)!
*Leftovers of this casserole are great for a couple of days after making it.
*Turn this casserole into a day-after- holiday meal by adding leftover turkey instead of chicken.