Preheat the oven to 225°F. Line two baking sheets with parchment paper.
Using a hand mixer in a stainless steel or glass bowl, beat egg whites on high speed until soft peaks form.
Add in cream of tartar and continue beating on high while very slowly adding the sugar.
When sugar is fully combined, turn the mixer off and transfer half (it's easier to do half at a time) of the meringue to a piping bag fitted with a large star tip (I use a Wilton 6B tip).
Pipe 15 meringues onto each pan (30 in all).
Add about ½ tsp dulce de leche onto each meringue and using a toothpick, swirl around to make a pattern on each meringue.
Put both baking sheets in the oven and bake for 45 minutes. After the 45 minutes is up, turn off the oven and let the meringues sit in the oven without opening the door for 1 hour (patience people!).
After the hour is up, take the meringues out of the oven to finish cooling.