This may be the one you're looking for! Very old recipe but worth all the steps.

WHITE CHRISTMAS PIE

FILLING:
1 Tbsp. unflavored gelatin
1/2 cup sugar
4 Tbsp. flour

Mix together.

Add:
3/4 tsp. vanilla
1 1/2 cups milk

Cook until bubbly and thickens.
Set aside and stir occasionally. Cool completely.

BEAT:
1 pint heavy (whipping) cream until stiff - set aside

BEAT:
3 egg whites (pasteurized)
1/4 tsp. cream of tartar
1/2 cup sugar

Beat egg whites till stiff, add cream of tartar, gradually add sugar. Set aside.

When filling is completely cooled, fold in whipped cream and egg white mixture.

ADD:
1/2 cup shredded coconut

Pour mixture into a baked pie shell.
Sprinkle more coconut on top of pie.

Makes 2 pies or 1 thick pie