My aunt has been making these every Christmas for all the kids in the family for as far back as I can remember. They're super quick, easy & CHEAP to make! And I haven't heard anyone ever say they didn't like them!!
Preheat oven to 250. Beat sugar & egg whites till fluffy. Add cream of tartar & beat till evenly distributed. Fold in M&Ms. With a teaspoon, spoon mixture into parchment paper-lined cookie sheets. Bake for 1hr.
**The "balls" turn out best if you make them on a day that's NOT cloudy, rainy or high in humidity!**