Creamed Chicken and biscuits

1/2 large onion chopped
1 1/4 tsp butter
4 Cups cooked chopped chicken
1 (10 3/4 oz) can cream of chicken soup
1 Cup sour cream
1/2 Cup milk
1/2 Cup chopped pimiento
1 Cup shredded Cheddar cheese
6 frozen biscuits, thawed

Heat butter in a small non-stick skillet over med-high heat. stir till melted, stir in onions, saute till tender, remove from heat.
Combine onion, chicken, soup, sour cream, milk and pimiento in mixing bowl and mix well.
Spoon into baking dish and bake for 15 min remove from oven. Sprinkle with 3/4 cup cheese and top with biscuits, sprinkle with remaining cheese. Bake until biscuits are golden brown and sauce is bubbly, about 20 min. Serve immediately.