Preheat oven to 350°F. Line a baking sheet with a Silpat liner or parchment paper.

Melt the butter in a saucepan over medium heat. Once the butter is melted, whisk constantly. It will foam, then brown on the bottom. Turn off heat as soon as solids turn brown and a nutty aroma appears.

Add the sugar to a medium bowl. Pour the brown butter over top, scraping the bottom of the pot for all milk solids. Whisk to combine. Add the egg and vanilla, then whisk until smooth.

Add the quick oats, flour, and salt and mix with a spatula to combine. Drop the dough by teaspoonfuls on the prepared baking sheet, leaving about 2 1/2 inches between the cookies. You should fit 12 per sheet; do not crowd them as they spread.

Bake for 12-14 minutes until the cookies turn golden brown. Remove from the oven and cool on the pan for 2-3 minutes.

Use a small spatula to flip 6 cookies over on the baking sheet. Top these with 10-12 chocolate chips, letting the pan's heat melt the chocolate. If it doesn't melt, return to oven for 1 minute. Spread the chocolate into a thin layer, then top with a second cookie. Transfer to a cooling rack to cool completely.

Store in an airtight container or resealable bag at room temperature for up to 4 days. Cookies can be frozen in a resealable bag for up to 3 months. Enjoy!