Heat oven to 400Â°.
Heat margarine in round pan, 9x 1 1/2 inches, in oven until melted.
Sprinkle brown sugar and nutmeg evenly over margarine.
Arrange pear slices in pan, overlapping slices slightly.
Beat egg whites in 1 1/2-quart bowl on high speed until stiff but not dry.
Beat egg yolks, milk, flour and baking powder in 1-quart bowl on low speed just until smooth, about 30 seconds.
Fold egg yolk mixture into beaten whites.
Pour batter over pears.
Bake until pancake is golden brown and firm, about 20 minutes.
Prepare Lemon Sauce.
Loosen edge of pancake with metal spatula; invert onto heatproof serving plate.
Let pan remain a few minutes.
Serve pancake with Lemon Sauce.