In a large heavy skillet, sauté boneless chicken breast pieces or chicken breast halves in 2 tablespoons butter until golden brown on all sides. Transfer chicken pieces to a 9 x 9 x2-inch baking dish; evenly pour sherry over chicken. Cover and bake in a preheated slow oven (325 degrees F.) for 30 minutes or until chicken is fork tender. While chicken is baking, prepare sauce. In a medium heavy skillet, sauté mushrooms in 2 tablespoons butter over moderate heat until just tender. Reduce heat and add flour, blending well. Stir in chicken broth, bay leaf, chives, tomato paste, and salt and pepper to taste, blending well; bring to a simmer. Add cooked seafood and simmer over low heat until heated through. To serve, arrange a boneless chicken piece or half breast on each dinner plate and spoon hot sauce over each serving, dividing evenly. Garnish each serving as desired.
Note: For larger servings, use 8 ounces boneless chicken per serving or 2 chicken half breasts per serving.
Variation: May add 1 to 2 warmed thin fully-cooked smoked ham slice(s) (about the size of each boneless breast piece or breast half) to each serving, if desired, just before serving.