What will adding an extra egg do to cookies?

Online Answer
Adding an extra egg yolk increases chewiness. Rolling the cookie dough balls to be taller than wider increases thickness. Using melted butter (and slightly more flour) increases chewiness. Chilling the dough results in a thicker cookie.
Related Questions 📌
Your baked goods won't stick to it, and when you're done you can throw out the parchment instead of washing the pan. If you have no parchment paper, you can still bakeyou'll just have to be a bit more creative..
So one way to get the best of both: Use half butter and half shortening. By the way "butter" here is butter. Real butter, not margarine.
If a recipe calls for a tablespoon of baking powder, you'll want to substitute with a teaspoon of baking soda. You'll also want to add 2 teaspoons of vinegar or lemon juice to your batter.