01 - Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together the all-purpose flour, cornstarch, baking powder, baking soda, salt, and ground cinnamon for the cookie dough.
03 - In a large bowl, cream together the softened unsalted butter, granulated sugar, and packed light brown sugar until the mixture is light and fluffy, approximately 2-3 minutes.
04 - Beat in the eggs one at a time, ensuring each is fully incorporated before adding the next. Stir in the pure vanilla extract and full-fat sour cream until the mixture is smooth.
05 - Gradually add the combined dry ingredients to the wet ingredients. Mix on low speed just until the ingredients are incorporated. Avoid overmixing to maintain a tender cookie texture.
06 - In a small bowl, combine the granulated sugar and ground cinnamon for the cookie topping.
07 - Using a medium cookie scoop or a spoon, portion approximately 2-tablespoon mounds of cookie dough onto the prepared baking sheets. Ensure they are spaced about 2 inches apart.
08 - Generously sprinkle the prepared cinnamon sugar topping over each mound of cookie dough.
09 - Bake for 9 to 11 minutes, or until the edges of the cookies are set but the centers still appear slightly underbaked. This timing is crucial for achieving a soft, cloud-like texture.
10 - Allow the cookies to cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.
11 - While the cookies are cooling, prepare the frosting. Beat the softened cream cheese and softened unsalted butter together until smooth. Add the sifted powdered sugar, pure vanilla extract, and salt, and continue beating until the frosting is fluffy.
12 - Once the cookies are completely cool, spread or pipe the cream cheese frosting onto the top of each cookie.
13 - Optionally, sprinkle additional cinnamon sugar over the frosted cookies before serving.