Combine butter and sugars in a large mixing bowl and use an electric mixer to beat until light, fluffy, and well-creamed.

Add eggs and vanilla extract and stir again until thoroughly combined. Set aside.

In a separate mixing bowl whisk together flour, cornstarch, baking powder, baking soda and salt.

Gradually add dry ingredients to wet, stirring until completely combined.

Cover dough tightly with plastic wrap and transfer to the refrigerator to chill for 30-60 minutes.

Meanwhile, prepare the filling.

In a mixing bowl, combine butter, sugar, and vanilla and stir or beat until smooth and creamy.

Sprinkle flour, cinnamon, and salt over the butter/sugar mixture and stir until well-combined.

Remove chilled cookie dough from the refrigerator and scoop by ¼ cup. Break the scoop in half and form one half into a nest.

Scoop a Tablespoon of the brown sugar filling into the nest. Form the other half of the cookie dough into a flattened nest shape and seal the filling inside.

Repeat until all cookie dough and filling is used.

Place cookie dough on a baking sheet and place in the freezer for 15-30 minutes.

Preheat your oven to 375F (190C) and line a baking sheet with parchment paper.

Once the dough has chilled and the oven is preheated, bake for 14 minutes.

Allow to cool completely on the baking sheet before icing.

In a bowl, combine powdered sugar, brown sugar, milk, corn syrup, vanilla extract, and cinnamon. Whisk until smooth.

Immediately drizzle over cooled cookies and allow to set before enjoying.