Creamy Chicken without fraiche pork breadcrumbs

1 teaspoon unsalted butter 4 skinless, boneless chicken breast halves 1 onion, finely diced 1 pound fresh asparagus, trimmed and cut into 2 1/2 inch pieces 1[...]

2 1/2 lbs chicken pieces (bone and skin in) 1 cup mayonnaise , tangy, not bland 4 tablespoons prepared mustard , preferably wholegrain and creamy 1 teaspoon[...]

2 1/2 lbs chicken pieces (bone and skin in) 1 cup mayonnaise , tangy, not bland 4 tablespoons prepared mustard , preferably wholegrain and creamy 1 teaspoon[...]