01 -
In a large bowl, beat the softened butter with brown sugar and granulated sugar until light and fluffy, about 3 minutes.
02 -
Incorporate the egg, egg yolk, vanilla extract, and lemon juice into the creamed butter mixture. Mix until thoroughly combined.
03 -
In a separate bowl, whisk together flour, cornstarch, baking powder, baking soda, cinnamon, and salt.
04 -
Gradually add the dry ingredients to the wet ingredients, stirring just until no dry flour remains. Avoid overmixing to keep cookies tender.
05 -
Mix granulated sugar and cinnamon in a shallow bowl for rolling the cookie dough balls.
06 -
Scoop 2.5 tablespoons of dough per cookie, roll each ball in the cinnamon sugar mixture to coat evenly, and place on a parchment-lined baking sheet about 2 inches apart.
07 -
Bake in a preheated oven at 350°F (177°C) for 10-12 minutes until edges are set and centers appear slightly underbaked.
08 -
Allow cookies to rest on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.
09 -
Beat softened butter until smooth, then slowly add powdered sugar and cinnamon. Mix in heavy cream and vanilla extract until light and fluffy.
10 -
Pipe or spread cinnamon buttercream onto cooled cookies, then sprinkle additional cinnamon sugar on top for garnish.