Position the oven racks in the upper and lower middle positions and preheat to 200 degrees. Line two baking sheets with parchment paper.
Wipe a whisk and the metal bowl of an electric mixer with lemon juice or vinegar to remove any trace of grease. Fill a saucepan with about an inch of water and heat until simmering.
Place the egg whites and granulated sugar into the metal bowl, then position the bowl over the saucepan. The bowl should fit snugly but should not touch the water to keep the eggs from cooking. Heat the mixture, whisking constantly, until a candy or instant-read thermometer reads 115 degrees or until the sugar has completely dissolved and the egg whites are hot.
Remove from heat and whip the mixture on high speed until the meringue is fluffy and the bowl is cool to the touch, about 10 minutes. Make the ganache while you wait on the meringue to cool. Gently fold the vanilla bean powder and sifted powdered sugar into the mixture with a spatula.
Place large spoonfuls of meringue in rough circles about ¾ inch tall and 3 inches round on the parchment paper. I had enough meringue to make about 14 meringues, or 7 meringue sandwiches. Bake for 1½ to 2 hours or until the bottoms sound hollow when you tap them. Turn the oven off and crack the oven door (I use a wooden spoon), leave the meringues in the oven to cool for about 30 minutes, this will help keep them from cooling too quickly which causes cracking.
Recipe by oh honey bakes at https://ohhoneybakes.com/vanilla-meringues-with-dark-chocolate-ganache/