1. Preheat your oven to 325°.
2. Line a baking sheet with parchment paper and set aside.
3. Melt your butter half way in the microwave.
4. Then, in the bowl of your stand mixer cream the butter with both of the sugars until smooth.
5. Add in the egg, egg yolk and vanilla and mix until completely combined.
6. Incorporate the flour, corn starch and baking soda on low until JUST combined.
7. Pour in your chocolate chunks and chips and mix them in by hand with a rubber spatula or spoon until they are evenly distributed.
8. Shape your dough into balls, a little bit higher than normal (refer to picture in post).
9. Place on your prepared baking sheet 1-1/2 in. apart and bake for 11-12 mins.
10. If you prefer a cookie with crunchy edges, bake for one extra minute.
Don't overbake! Cookies may seem to be underdone, but they aren't. They will firm up as they cool.