In a medium bowl, whisk together the flour, cornstarch, baking soda, and fine sea salt. Set aside.

In a large mixing bowl, whisk melted butter, packed brown sugar, and granulated sugar together until completely smooth and emulsified without lumps.

Whisk in the whole egg, egg yolk, and vanilla extract until glossy and fully combined.

Pour dry ingredients into wet ingredients and fold gently with a silicone spatula just until a soft dough forms. Do not overmix.

Fold in 3/4 cup of white chocolate chips and 3/4 cup of dried cranberries, reserving the remaining for pressing onto tops before baking.

Cover dough and chill in the refrigerator for 30 minutes (helps prevent cookies from spreading thin and enhances chewiness).

Preheat oven to 350°F (177°C) and line two large baking sheets with parchment paper.

Scoop dough into 1.5-tablespoon balls (using a cookie scoop) and place 2 inches apart. Press reserved cranberries and white chocolate chips gently into top surfaces for a bakery-style presentation.

Bake for 10 to 12 minutes until edges are set and very lightly golden, while the center still appears soft and pale. Cool on pan for 5 minutes, then transfer to a wire rack to firm up.