Start by softening the butter until it’s creamy but not melted.
Mix it with both the brown and granulated sugars, creaming them together until light and fluffy, this step is key for chewy cookies.
Incorporate the eggs one at a time, mixing thoroughly after each addition, then blend in the vanilla extract.
In a separate bowl, whisk the flour, oats, baking soda, and salt. Mixing the dry ingredients separately helps everything blend evenly.
Gradually add the dry mixture to the wet ingredients, stirring gently until just combined, don’t overmix to keep the cookies soft.
Fold in the semi-sweet and milk chocolate chunks.
For extra-chocolatey cookies, save a few chunks to press into the tops before baking.
Scoop dough onto a lined baking sheet and chill for 30 minutes to help the cookies bake thick and chewy.
Preheat the oven, then bake the cookies for 10 minutes until the edges are golden and the centers are slightly soft.
Let them cool on the baking sheet for a few minutes before transferring to a rack. Enjoy!