Insert the butterfly into the TM bowl.
Add the room temperature butter, caster sugar and vanilla extract and mix on Speed 3 for 90 seconds (scrape down the sides of the bowl partway through).
Take the butterfly out of the TM bowl. Add the egg and mix on Speed 5 for 10 seconds. Scrape down the sides of the bowl and repeat for a further 10 seconds.
Add the plain flour, cream of tartar, bi-carb soda and salt and mix on Speed 4 for 20 seconds.
Scrape down the sides of the bowl and repeat for a further 10 seconds.
At this stage the mixture will be quite sticky - place it into a bowl and then into the fridge for a minimum of 30 minutes.
Meanwhile, make the cinnamon sugar coating by placing the cinnamon and extra caster sugar into the TM bowl and mixing for 5 seconds on Speed 8.
Place the cinnamon sugar into a bowl.
Preheat the oven to 200 degrees celsius.
Line two baking trays with baking paper.
Remove the cookie dough from the fridge.
Roll the dough into teaspoon-sized balls and then coat in the cinnamon sugar mixture.
Allow a 5cm gap between each snickerdoodle on the baking trays as they will spread.
Bake in the oven for 8-10mins or until the cookies appear slightly puffed, lightly golden and set in the middle.
Leave the snickerdoodles to cool on baking tray for 10 mins before transferring to a wire rack to cool completely.