Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper to prevent sticking and ensure even baking.

In a large mixing bowl, cream together the softened butter, granulated sugar, and brown sugar using an electric mixer on medium speed until light and fluffy, about 3-4 minutes. This step incorporates air into the mixture, which helps the cookies rise.

Add the eggs one at a time, mixing well after each addition. Then, stir in the vanilla extract. This ensures that the eggs are fully incorporated and adds flavor.

In a separate bowl, whisk together the sifted flour, baking powder, baking soda, and salt. This helps to evenly distribute the leavening agents and salt throughout the flour.

Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Be careful not to overmix, as this can lead to tough cookies.

Finally, fold in the sour cream until fully incorporated. This adds moisture and richness to the cookies.

In a small bowl, combine the granulated sugar and ground cinnamon. Mix well to ensure an even distribution of cinnamon.

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

Sprinkle the cinnamon sugar topping generously over each cookie dough ball. This will create a deliciously sweet and spiced crust.

Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden. The centers may look slightly underbaked; they will continue to firm up as they cool.

Remove from the oven and allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a cooling rack to cool completely.