In a large mixing bowl, use an electric mixer to beat butter and sugars until light and fluffy.

Add eggs and vanilla and stir to combine.

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

Gradually add dry ingredients into wet, stirring thoroughly after each addition, ensuring all ingredients are incorporated.

Cover bowl with plastic wrap and refrigerate to chill for 30 minutes.

Preheat oven to 350?F (175?C) and line baking sheets with parchment paper.

Scoop dough by 2-Tablespoon (45g) sized scoops and roll into smooth balls. Place on prepared baking sheet, spacing cookies at least 2? (5cm) apart.

Bake for 10-12 minutes until bottom edges start to turn slightly brown.

Immediately after removing from oven, create an indent in the cookie for the filling.

Bake and cool all cookies before preparing the topping.

In a medium-sized saucepan, combine sugar, butter, corn syrup, and salt. Heat over medium/low heat, stirring frequently until mixture boils and reaches 236-240?F (113-116?C).

Remove from heat and stir in chopped pecans, cream, and vanilla.

Allow filling to cool for 5 minutes before scooping into the indent of the cooled cookies.