Cover the chicken breasts with plastic wrap and pound them to about ½-inch thick with a kitchen mallet. Dissolve the salt in the water, add the chicken, then cover and chill for exactly 1 hour. When the chicken is done marinating, remove it from the brine, rinse it off, and blot it dry. Heat up 1 tablespoon of oil in a medium saute pan over medium/high heat and cook the chicken in the pan for 3 to 5 minutes per side, or until it's cooked through. Cool and chop the chicken into bite-sized chunks.
Make the alfredo sauce by melting the butter in a medium saucepan over medium/low heat. Add the garlic and cook for 1 minute. Add the remaining ingredients and increase the heat to medium. When the sauce begins to boil, reduce the heat and simmer for 12 minutes, or until thickened.
Cook the pasta in 3 to 4 quarts of boiling water for 8 minutes, or until tender. Drain.
Preheat the broiler to high.
Pour the pasta into a 9x13-inch baking pan. Pour the Alfredo sauce over the pasta and toss to coat all of the pasta. Sprinkle the chicken over the top of the pasta, then cover with shredded cheese.
Broil 2 to 3 minutes, or until the cheese begins to brown.
