Fettuccini Alfredo with Shrimp and Chicken

Thank you, Jim! This recipe was a treat made for me, and it was so good I just had to share. It's from Allrecipes.com with shrimp added. Be warned: it makes enough to feed an army! If you cut it in half, you'll have more than 4 generous servings.

6 boneless, skinless chicken breast halves, cut into cubes
6 tbsp. butter, divided
4 cloves garlic, minced, divided
1 tbsp. Italian seasoning
1 lb. fettuccini pasta
1 onion, diced
1 (8 oz.) package sliced mushrooms
1/3 c. all purpose flour
1 tbsp. salt
3/4 tsp. ground white pepper
3 c. milk
1 c. half-and-half
3/4 c. grated parmesan cheese
8 oz. shredded Colby-Jack cheese
3 roma (plum) tomatoes, diced
12-16 cooked large shrimp
1/2 c. sour cream

1. In a large skillet over medium heat, combine chicken, 2 tbsp. butter, garlic and Italian seasoning. Cook until chicken is no longer pink inside, remove from skillet, and set aside.
2. Bring a large pot of lightly salted water to a boil. Add pasta and cook for 8 to 10 minutes until al dente; drain.
3. Meanwhile, melt 4 tbsp. butter in the skillet. Saute onion, 2 tbsp. garlic and mushrooms until onions are transparent. Stir in flour, salt and pepper; cook 2 minutes.
4. Slowly add milk and half-and-half, stirring until smooth and creamy. Stir in parmesan and Colby-Jack cheeses; stir until cheese is melted. Stir in chicken mixture, tomatoes, shrimp and sour cream.
5. Serve over cooked fettuccini.

The only change we could think of to make was to replace a little bit of the white pepper with some freshly ground black pepper, since the flavor of the white pepper is strong. Also, this sauce is great reheated! It doesn't separate.