Preheat the oven to 350.
In a mixer, cream together butter and sugar until white and fluffy.
Add egg and vanilla. Make sure to add the entire amount of vanilla. The batter needs that amount of liquid to come together.
Finally, mix in the flour, salt, and baking powder. The mixture will look crumbly, but will come together. If after a minute of mixing it hasn’t come together yet, add in a teaspoon of water and mix again.
Place the dough into a 1/4 measuring cup and then form it into a ball.
Roll the dough ball into the cinnamon sugar mixture and place on the cookie sheet.
Bake for 10-12 minutes. Not longer!
Let cookies cool on the cookie sheet for 5 minutes and then transfer to the cookie rack to cool completely.