Prepare stuffing mix per package instructions, substituting 2 tablespoons olive oil and 1 rounded teaspoon garlic powder for the margarine specified on the stuffing package.
Melt 3 to 4 tablespoons margarine in a skillet. Dust chicken with pepper and garlic salt. Brown chicken in margarine.
Spread the prepared stuffing in a large (9" x 13") glass baking dish. Arrange chicken on stuffing, pressing chicken pieces slightly into the stuffing.
Use the pot in which you prepared the stuffing to mix the sauce. Don't worry if there are slight bits of stuffing or herbs left in the pot.
Scrape any remaining margarine and chicken bits from the skillet into the pot. Add the soup, mayonnaise, evaporated milk, water and garlic salt. Whisk together. Heat on medium, stirring frequently. When hot, add peppers, pimientos and Velveeta. Continue to stir until cheese melts and sauce is thoroughly mixed.
Pour sauce over chicken and stuffing. Bake uncovered at 350°F for 1 hour.