Preheat oven to 200°F. Line 2 baking sheets with parchment paper, set aside.
In the bowl of a stand mixer combine the egg whites, sugar and salt. It will be very thick and grainy. Put the bowl over a double boiler and stir with a rubber spatula until the sugar is completely melted. This can take several minutes. You want to brush the sides down with the spatula to make sure all the sugar is melted and no grains are clinging to the sides.
Feel the egg mixture between your fingers to check for graininess. Once it is completely smooth, put it on your stand mixer and beat with the whip attachment on medium high speed.
Beat it until it is light, fluffy, glossy and the bowl feels just about room temperature. Add the scraped vanilla seeds and whip until they are evenly distributed.
Use a spoon to create mounds of the meringue on the parchment. Wet the spoon and make a well in the center of the mound.
Bake the meringues for an 1 1/2 hours. Turn off the heat and allow the meringues to sit in the oven for 30 more minutes. Remove from the oven and let cool completely before filling.