Heat butter in Dutch oven over medium-high heat until hot. Add onion, garlic,
thyme, sage and pepper. Cook and stir 3 to 5 minutes until onion is tender.
Add flour, cook and stir 1 to 2 minutes. Whisk in broth; cook, whisking 4 to
6 minutes or until sauce boils and thickens. Stir in vegetables; cook 5 to 7
minutes or until vegetables are tender. Stir in rice, chicken and parsley;
cook, stirring 2 to 3 minutes more. Place in 2-1/2-quart casserole. (May be
prepared 1 day ahead. Cover and refrigerate. Bring to room temperature before
baking.) Combine baking mix, buttermilk and onions in medium bowl. Gently stir,
just until dough comes together. Form dough into 9-inch long log on lightly
floured surface; cut crosswise into 6-1/2-inch rounds. (Or roll out dough on
lightly floured surface to 1/2-inch thickness and cut with different shaped
cookie cutters.) Top casserole with biscuits, spacing evenly. Bake in 425-degree
oven for 20 minutes until filling is bubbly and biscuits are golden brown.