1.Heat oven to 350°F. Spray a 10-ounce ramekin with with cooking spray and set aside.
2.In a small bowl, whisk together the sugar, flour, salt and cocoa powder until thoroughly combined. Add the melted butter, egg yolk, and vanilla. Stir with a rubber spatula to combine. Do not overmix.
3.Fold in the chocolate chips and 2 crumbled Oreo cookies. Pour the batter into the prepared ramekin. Spread into an even layer and top with 1 tablespoon of chocolate chips and 1 crumbled Oreo cookie. Bake for 30 minutes.
4.Remove from the oven and let cool for 5 minutes before enjoying.