Mam-ma's Chocolate Pie

My sweet mam-ma made the BEST chocolate pie. We used to request it at every holiday dinner or family gathering and it was a fight to see who could eat the most. I have never tried to make it until this weekend. It tasted good but I have a long way to go on being able to make a good meringue. I don't know what the secret it is but I hope one day I can get mine to fluff up like hers always did.

Ingredients:
Pie filling:
Frozen or refrigerated pie crust
1 3/4 cup sugar
3 tbsp cornstarch
3-4 tbsp cocoa
1 1/2 cups milk
4 egg yolks
1 tbsp vanilla
2 tbsp butter

Meringue:
4 egg whites
1/2 cup sugar
6-8 large marshmallows

Bake pie crust according to directions. Mix first 3 ingredients. Beat 4 egg yolks and save the whites. Sprinkle salt on eggs. Add milk in eggs. Add to dry and cook on stove top - stir until thick. Add vanilla and butter.
Pour in pie crust when done.

Take egg whites and beat until stiff. Take sugar and a "tad" of water and boil until it makes a syrup. Add marshmallows and melt.  Add to egg whites already beat. Add on top of pie.