Preheat oven to 350°F. Line 2 baking sheets with parchment paper. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment, beat the butter and brown sugar on medium speed until well combined, about 1 minute.
½ cup salted butter, 1 cup brown sugar
Add the egg and vanilla extract and mix to combine. Make sure to scrape down the sides of the bowl as necessary.
1 large egg, 1 teaspoon pure vanilla extract
Add in the oats, flour, and baking soda. Mix on low speed, just until combined. You don’t want to overmix!
1½ cups old fashioned oats, ¾ cup all-purpose flour, ¾ teaspoon baking soda
Gently fold in the chocolate chips/chunks. I don’t recommend using the mixer attachment for this part as it can break up the chocolate too much.
1 cup chocolate chips
Scoop the dough into 2 tablespoon-sized scoops and place them at least 2 inches apart on the prepared baking sheets.
Bake for 12-14 minutes, or until the cookies are set around the edges and just starting to turn golden brown on the bottom. The cookies will be soft but they will harden as they cool.
Allow the cookies to cool to room temperature on the baking sheet before transferring to a wire rack.