In the bowl of a stand mixer fitted with a paddle attachment, cream room-temperature butter until smooth.
Add both sugars and vanilla, then beat on medium speed for 5 minutes, scraping down the sides occasionally.
Add corn syrup and mix for another 3 minutes.
Add one egg and mix until fully incorporated. Repeat with the second egg.
Add baking soda, baking powder, cornstarch, and salt. Mix well.
Add milk powder and mix again.
Add in the chocolate chips and mix until evenly distributed.
Add the flour in 2-cup increments, mixing just until incorporated after each addition. Avoid overmixing once the flour is fully combined.
Remove the paddle attachment, scrape down the sides.
Optional: Cover and chill the dough for at least 2 hours. If freezing, portion the dough first for easier baking.
When ready to bake, preheat the oven to 375°F and line three (3) cookie sheets with parchment paper.
Use a ½-ounce or 1-ounce scoop to portion the dough. Roll each portion into a smooth ball if necessary, and space the dough balls 2 inches apart on the baking sheet to allow for some spreading.
Bake large cookies for 5-6 minutes. If baking in a standard oven (not convection), rotate the pan halfway to ensure an even bake.
The cookies are ready when they’re a light golden brown. Be careful not to let the edges get dark.
Remove from oven and let cookies sit on the warm baking sheet for another 20 minutes to continue slowly baking out of the oven.
Serve warm.