Preheat oven to 350F degrees.

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

In a large bowl using an electric mixer, cream together butter and sugars on medium speed. Add egg yolk and vanilla extract; mix until combined.

Slowly add flour mixture to wet ingredients; mix just until combined. Do not overmix.

Gently fold in mini chocolate chips.

Scoop dough into heaping tablespoon balls, or use a #40 disher to scoop balls of dough. Place on a ungreased baking sheet, or silicone mat/parchment paper lined baking sheet.

Bake 8-10 minutes or until barely golden brown around the edges. Do not overbake. The tops will not brown. Do not bake longer than 10 minutes. Mine baked perfect at 9 minutes. Cookies may appear to be soft and undone, but they will set as they cool.

Cool cookies on baking sheet on wire rack for 5 minutes; transfer to a wire rack to cool completely. Eat & Enjoy!