- In a bowl, combine the sugar and cinnamon. Set aside.
- In another bowl, combine the flour, baking powder, cream of tartar and salt.
- In a third bowl, cream the butter and sugar with an electric mixer. Add the eggs and whisk until smooth. With the machine running on low speed or with a wooden spoon, add the dry ingredients.
- Form the mixture into balls using about 2 tbsp for each one. Roll the balls one at a time in the coating and place on a large plate. Freeze the balls for 1 hour or until firm (see note). At this point, you can place the balls in an airtight container or freezer bag and freeze for up to 3 months, if desired.
- With the rack in the middle position, preheat the oven to 400°F (200°C). Line two baking sheets with silicone mats or parchment paper. Place 12 frozen cookies on each baking sheet.
- Bake one sheet at a time for 10 minutes. The cookies will puff up slightly and will not be completely cooked through at the centre. Let cool completely on the baking sheets. The cookies will deflate as they cool.
- The snickerdoodles will keep for 3 to 4 days in an airtight container at room temperature.
Snickerdoodles are at their best when the dough has been frozen. This will help the dough hold together as the cookies bake.