Add the egg whites and salt to a mixer fitted with a wire whipping attachment. Make sure the egg whites are used at room temperature and the bowl is fat free. Whip on medium speed for 3 minutes. When frothy, start adding sugar a teaspoon at a time stopping 2 – 3 times to scrape the sides of the bowl. Add in the Cream of Tartar and vanilla and continue to whip on high speed until stiff peaks form.
Transfer meringue to a piping bag fitted with a Wilton 1M tip. Pipe 3 – 4 inch base first, then pipe up around sides to form a bowl.
Bake at 200° F (90° C) for 1 hour. Turn the cookie sheet around and bake for another 45 minutes. When done, simply turn off the heat, turn on the light, and leave overnight in the oven to cool.
For the White Chocolate Mousse
Place the chopped white chocolate into a large glass bowl and set aside.
Add the egg yolks and sugar to a small bowl and whisk until pale in color.
In a saucepan, over low heat, bring 1/4 cup of the cream to a simmer, and slowly add the cream into the yolk and sugar mixture to temper. Pour the creamy mixture back into the pan and stir with a wooden spoon until it coats the back of it.
Pour the hot mixture over the chopped chocolate. Stir until completely smooth.
In another bowl, whip cream to almost stiff peaks. Fold 1/2 of whipped cream into the white chocolate mixture then add the remaining half.
Let Mousse sit in the fridge for 1 hour to set up.
Spoon the Mousse into the Meringue Shells and top with whipped cream and coconut.