Preheat the oven to 350 degrees Fahrenheit (175 degrees Celsius). Line baking sheets with parchment paper or silicone mats.

In a mixing bowl, whisk together 2 ½ cups all-purpose flour, cornstarch, baking soda, and sea salt. Set aside.

In another bowl, cream together softened butter, 1 cup of brown sugar, granulated sugar, until light and fluffy. Add the egg, egg yolk, and vanilla extract, mixing until well combined.

Gradually add the dry ingredients to the wet ingredients, mixing until a cookie dough forms. Do not overmix. Set aside the dough.

For the pecan topping, melt 5 tablespoons of unsalted butter in a saucepan over medium heat. Stir in dark brown sugar, maple syrup, chopped pecans, and a pinch of salt. Cook until slightly thickened. Add heavy cream and vanilla, cook for an additional 1 minute. Remove from heat and let it cool.

Take 1/4 cup portions of the cookie dough, roll them into balls, and place on the prepared baking sheets. Refrigerate overnight or freeze for 1-2 hours.

When ready to bake, preheat the oven. Bake the cookies for 12-13 minutes or until the edges are golden brown.

Immediately press down the center of each cookie with the back of a measuring spoon to create a well.

Allow the cookies to cool on the baking sheets for a few minutes before transferring them to a wire rack to cool completely.

Top each cookie with a large tablespoon of the pecan mixture and sprinkle with flaky sea salt.

Enjoy these irresistible pecan pie cookies with their perfect blend of textures!