Whisk flour, baking powder, and salt together in a small mixing bowl and set aside.
Add butter and sugar to a large mixing bowl (or the bowl of a stand mixer fitted with a paddle attachment). If not using a stand mixer, use a handheld mixer to beat the butter & sugar for about 3 minutes, until fluffy.
Add egg and vanilla and beat again until well combined.
Add dry ingredients gradually, on low speed, and mix well. This is a relatively stiff dough and may seem crumbly at first, but it should come together.
I highly recommend chilling the dough for at least a couple hours for a much easier time with shaping and an improved final texture & flavor.
Use a spatula to scoop the dough onto a sheet of plastic wrap, wrap it up fully and put it in the fridge for 2 hours-overnight.
Before you're ready to shape, preheat the oven to 350 degrees and line a couple of baking sheets with parchment paper.
Stir the sugar and cinnamon for the topping together in a very shallow bowl or on a plate.
If you want to use a kitchen scale to measure, this recipe will make 25 cookies of approximately 25 grams each.
Use a knife or a bench knife to pinch off a 25 gram piece of dough and roll it out into a cylinder about 1/2 inch thick. Roll the dough in the cinnamon sugar mixture.
Shape the dough into an "S" and place it on the prepared baking sheet.
Repeat with the remaining dough.
Bake for 8-11 minutes, until set. Let cool on the baking sheet for 5 minutes, then use a spatula to remove to a wire rack to cool fully.
These keep on the counter in an airtight container for about 3 days.