ITALIAN SPINACH-RICOTTA PIE

1 pre baked pie shell (follow directions on package)
1 tbs. butter or margarine
1 cup minced onion
1 10 oz. package frozen chopped spinach, thawed
1 15 oz. container Ricotta cheese
2 eggs
3/4 tsp. salt
1/4 tsp. pepper
1/4 tsp. ground nutmeg
1/2 cup freshly grated parmesan cheese

Thoroughly drain spinach, using hands to squeeze out as much moisture as possible.  Melt butter and fry onion until soft.  Add spinach and stir until most of the moisture is gone.  Remove from heat.  In large bowl add all the other ingredients to the spinach and stir until mixture looks like green and white marble.  Pour into baked pie shell. Bake at 350 degrees for abut 40 minutes, or until top is golden and filling is set.  Sometimes I add some sliced tomatoes to the top of the pie about 10 minutes before it is completely baked.  It looks more attractive, and really does add to the flavor.