Combine 1/2 cup sugar, 3 egg yolks,milk, salt, cinnamon, ginger, and nutmeg with 1-1/2 cups pumpkin in double boiler until thick. Remove from heat, add gelatin and stir well. Chill until it begins to thicken. Then beat egg whites frothy, add 1 cup sugar and beat until stiff. Fold into pumpkin mixture. Pour into pie shell and cool. Serve with whipped cream and sprinkle with a little nutmeg.