Preheat oven to 300 F (150 C).
Separate egg whites from egg yolks and add to a dry deep bowl. Add lemon juice.
Whisk for 1 minute until they become white. Add vanilla extract and gradually add sugar about 1 Tablespoon at a time, stirring after each addition until sugar is dissolved. Using an electric mixer or a stand mixer, whisk the mixture on high speed for 10-12 minutes.
The mixture should be thick, shiny, and has increased in volume.
The mixture should have stiff peaks and sugar should be completely dissolved (you can test this by rubbing a small bit of the mixture between your fingers, if it feels gritty, the sugar isn't dissolved).
Stir in chocolate chips and nuts or any other extra topping you may like to use. If using food coloring, add the food coloring at this stage, too.
Instead of sugar powder, you can also use granulated sugar BUT you need to make sure that it will dissolve properly.
Fit a large disposable piping bag with a large tip and transfer the meringue to the prepared piping bag and pipe onto the prepared cookie sheet. The meringue cookies can be pretty close to each other as they won’t spread, and you will want to bake all of the cookies at the same time, so make sure you make enough space.
I like it when the meringues are crisp, and chewy on the inside. The short baking time allows them to have this right texture.
Top with cake sprinkles if you like and bake for 20 minutes in the middle of the oven.
Allow to cool completely on the baking sheet before removing them carefully with your hands.