Melt butter in 1 quart glass casserole in a microwave for 30 seconds. Add flour,
salt and pepper; mix well. Add milk gradually, stirring constantly.
Cook
uncovered in microwave for 3-4 minutes, or until thickened; stir after first 2
minutes, then after each 30 seconds.
Pare potatoes and thinly slice them. Put half of the potatoes into greased 2 quart
glass casserole.
Cover with half the onion and half the sauce. Repeat layers. Cover
with glass lid or plastic wrap. Cook in microwave 15-17 minutes, or until potatoes
are tender; stir every 5 minutes.
