Marshmallow fluff is a great treat that you can make at home.
Mix cream of tartar with just a few drops of water to eliminate the lumps. Add this to the egg white(s).
Place sugar, corn syrup, and water in a small saucepan. Gently stir to combine ingredients and make sure the sugar is wet. Heat to 248° F (120° C) without stirring.
When the temperature reaches 212° F (100°C) turn the mixer on medium-high. When the sugar mixture reaches the proper temperature, remove the syrup and pour a slow stream of the syrup into the whipping egg white(s).
Whip the marshmallow fluff until the outside of the bowl is cool to the touch. Transfer to a container or jar which seals and store in the refrigerator.
The fluff will hold a shape right after being made. Give it overnight in the cooler to take the familiar consistency that pours.
Boiling sugar can be tricky. This mixture has enough corn syrup that any issue should be well managed.
Vanilla is potent and too much can be overpowering.