Melt butter in large nonstick skillet on medium-high heat. Add onion; cook and stir 5 minutes or until softened. Sprinkle with flour. Stir with whisk until mixture is well blended. Add stock, 1 cup of the milk and all of the spices; whisk until mixture is smooth.
Stir in chicken and vegetables. Bring to boil; reduce heat to medium.
Mix baking mix and remaining 1/3 cup of milk until blended. Drop by spoonfuls onto chicken mixture. Cook, uncovered, 10 minutes. Cover. Cook 10 minutes longer. Let stand 5 minutes before serving.