Preheat oven to 350°F. Line two baking sheets with parchment paper.
Beat the butter, brown sugar, and granulated sugar on medium-high speed for 2 minutes using the paddle attachment of a stand mixer until smooth and creamy. Add the eggs and vanilla, then beat again, scraping down the sides of the bowl.
1 cup salted butter, 1 cup light brown sugar, 1/2 cup granulated sugar, 2 large eggs, 2 teaspoons pure vanilla extract
Add the oats, flour, baking soda, baking powder, and salt, mixing again until combined.
3 cups old-fashioned oats, 1 3/4 cups all-purpose flour, 1 teaspoon baking soda, 1/2 teaspoon baking powder, 1/2 teaspoon salt
Stir in chocolate chips, then use a large cookie scoop to scoop balls of dough and space them a few inches apart on a baking sheet lined with parchment paper.
2 cups semisweet chocolate chips
Bake for 9-11 minutes, until brown around the edges but the middle still looks slightly underbaked. The cookies will continue to set up as they cool, but underbaking helps them stay soft and chewy.