Preheat your oven to 350°F (175°C).

In a large bowl, whisk together the flour, baking powder, baking soda, and salt until well combined.

In a separate bowl, cream the softened butter and sugar together until light and fluffy.

Beat in the egg and vanilla extract until fully incorporated.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

In a small bowl, mix together the ground cinnamon and a sprinkle of sugar, then gently fold this into your cookie dough.

Using a cookie scoop or tablespoon, drop rounded balls of dough onto a lined baking sheet, spacing them about 2 inches apart.

Bake for 10-12 minutes, or until the edges start to turn a light golden brown.

Let your cookies cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.

Whisk together powdered sugar and milk until smooth, then drizzle over cooled cookies.