• Preheat oven to 325° Fahrenheit. Line the baking sheet pans with parchment paper or silicone baking sheets.
• Whisk the flour, cornstarch, baking soda and salt in a medium bowl.
• In a stand mixer, fitted with paddle attachment, beat the butter, brown sugar, and granulated sugar together on a medium-high speed until combined and creamy.
• Add egg, egg yolk, vanilla extract to the butter+sugar mixture. Beat on medium-high speed until combined. Scrape down the sides and up the bottom of the bowl as needed .
• Add dry ingredients(flour mixture) on a low speed. Add Chocolate chips. Mix until combined. The cookie dough will be thick.
• Take an ice-cream scoop and scoop out about 2 tablespoons of the dough. Shape each into mound. Place them 2 inches apart onto the lined cookie sheet.
• Bake 12 to 14 minutes or slightly brown at the edges. At this time center of the cookie will be soft. Cool for 15 minutes, remove from cookie sheet. Cool on wire rack. Enjoy cookies with a glass of milk.

Notes

• You can make the cookie dough and chill it in the refrigerator for upto 2-3 days. When ready to bake, bring the dough to room temperature and proceed to step 6.
• Baked cookies freeze well for up to 3 months.
• Unbaked cookie dough balls freeze well for up to 3 months. When ready to bake, remove from the freezer and bake. You might have to bake for a minute or two longer since the dough is frozen.
• Room temperature egg and egg yolk work best not only in this recipe but in any baking recipe. To bring the eggs to room temperature quickly, simply place the eggs in a glass of warm water for 5-10 minutes.
• Use room temperature softened butter. Please dont use melted butter as it does not cream well with sugar. Again its a good practice to use room temeperature butter in any baking recipe.
• Omit salt if you are using salted butter.