Preheat oven to 225F.
Line 2 quarter sheet baking pans (or two cookie sheets) with parchment paper.
Combine egg whites, cream of tartar, and salt in a large bowl (make sure the bowl is it is clean and dry - water or grease will prevent egg whites from whipping up.)
Beat the egg whites on low until foamy.
Increase mixer speed to high.
Gradually add white sugar, about 1 Tablespoon at a time - mixing well between each addition.
Once white sugar is well mixed add in Signature Flavored sugar 1 Tablespoon at a time - mixing well between additions (as above).
Continue beating the egg and sugar mixture until it is thick and shiny. It will increase in volume.
Beat until the egg whites form stiff peaks.
Stir in vanilla (or other flavoring) or food coloring if you wish and mix until well combined.
Using a small cookie scoop that has been sprayed with nonstick cooking spray, place scoopfuls of batter on the cookie sheets. You can use a piping bag with a decorating tip to pipe the cookies onto the baking sheet if you wish.
These cookies will not spread, so they can be close together on the baking sheets. The batter will not last so make sure there is room enough or all of them on your baking sheets.
Bake on 225F (105C) for 3 hours. Turn off the oven. Do not opne the door and leave them in the oven overnight (or until completely cooled - 6 to 8 hours).
Store in an airtight container. Keep away from heat and moisture as it can soften your meringues. If they get soft, you can put them in the oven at 225 for 10 or 15 minutes to crisp them up again.