Combine egg yolks, 1/2 the sugar, pumpkin, milk, salt and spice. Cook in top of double boiler until thick. Soak gelatin in cold water for 5 minutes, add to pumpkin mixture which has been removed from heat. Mix and cool. When thickened, beat egg whites until foamy, then gradually add remaining sugar. Beat until egg whites hold peak. Fold into pumpkin mixture. Pour into 9-inch baked pastry shell. (I used a quiche dish.) Chill. Garnish with whipped cream.