Preheat & Prep:
Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper.

Cream Butter & Sugars:
In a large bowl, beat the butter, brown sugar, and granulated sugar together until light and fluffy (about 2 minutes).

Add Wet Ingredients:
Mix in the eggs one at a time, then add the vanilla extract and mix until smooth.

Combine Dry Ingredients:
In a separate bowl, whisk together the flour, cornstarch, baking soda, and salt.

Mix Dry & Wet Ingredients:
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Fold in Chocolate Chips:
Stir in the semi-sweet and milk chocolate chips, ensuring they are evenly distributed.

Scoop & Shape:
Using a large cookie scoop (about ¼ cup), place dough balls onto the prepared baking sheet, spacing them about 3 inches apart.

Bake to Perfection:
Bake for 10-12 minutes, until the edges are lightly golden and the centers still look slightly underbaked.

Cool & Enjoy:
Let the cookies rest on the baking sheet for 10 minutes before transferring them to a wire rack. This helps them set and stay soft in the center.