8. Add Sugar and Beat to Stiff Peaks
While continuing to mix on medium speed, slowly add the granulated sugar 1 teaspoon at a time, letting each teaspoon of sugar mix into the egg whites before adding the next. This step should take about 5 minutes.
Once all the sugar has been added, stop the mixer and, with a spatula, scrape down any sugar granules that may be sticking to the side of the bowl.
Turn the mixer back on and adjust the speed to medium-high. Beat until stiff peaks form, 3 to 7 more minutes. You want to be careful not to over whip the egg whites, so when you know it is getting close, check them every 30 seconds