1. Grill chicken and slice into thin strips. Cook and drain pasta. Slowly cook onion in a little oil until onion is a rich brown.
2. Prepare southwestern pasta sauce: Melt butter; add flour. Stir until well combined. Add half-and-half, salt, and pepper. Stir with a whisk and continue cooking over medium-low heat until sauce is thickened and bubbly. Add cheeses and stir until blended. Add sour cream and mix well. Add chipotle peppers (chipotle peppers are hot; add more or less to taste) and chopped cilantro.
3. Pour four cups southwestern pasta sauce into a heated saute pan. Add pasta and chicken; toss to coat. After mixture is heated through, pour into a serving bowl. Garnish with chopped tomatoes, caramelized onions, and cilantro. Serves 4.
Note: You could substitute Perfect Poached Chicken in this recipe OR You can use 3 cups of Chunky Seasoned Chicken, defrosted if frozen, and omit caramelizing onions in step 1 above, if desired..