Prepare biscuit dough with biscuit mix with 1/2 cup of milk. On a lightly floured bowl, pat out dough to about 1/2-inch thickness; cut into 9 biscuits about 2 1/2 inches in diameter. Cut remaining dough into tiny biscuits, rounds or squares.
Melt butter in saucepan; add flour, stirring until smooth and bubbly. Add pepper, mace, Worcestershire sauce, herbs, milk, and chicken broth. Cook, stirring, until thickened.
Arrange onions, chicken, and peas and carrots in a lightly buttered 2-quart casserole; pour sauce over all. Arrange biscuits around top of pie. Brush with more half-and-half or milk. Bake chicken pie at 425° until browned and done, about 25 to 30 minutes.
Calories per serving: 500