Preheat oven to 200 degrees and line baking sheet with parchment paper.
Add egg whites in a bowl in a stand mixture and beat eggs at a low speed until foamy and add cream of tartar and continue to beat until it hold soft peaks.
Add sugar from time to time and coming to beat on a medium speed, beat in vanilla.
But the mixture on the baking sheet and bake approximately 1 1/2 hours to 1 3/4 hours.
Rotating the baking sheet about half way.
Turn off the oven and open a crack to leave the treat finish off drying for several hours or overnight.