Line two sheet pans with parchment paper or use a brown paper grocery bag. Set aside.
Add the egg whites to a mixing bowl. Using electric beaters, beat the egg whites until frothy and foamy. Sprinkle in the cream of tartar and beat on high speed for 1 minute. Sprinkle on the powdered sugar and beat on high for 1 - 1 1/2 minutes, until soft and glossy. Sprinkle on the granulated sugar and beat on high until stiff peaks form, another 2 or so minutes.
Drop spoonfuls of meringue onto the parchment paper or brown paper bag, about 2 inches apart.
Bake for 2 hours until meringues have dried out and set. Remove from oven and cool.