Heat oven to 350°F (177°C). Lightly butter a 10-ounce ramekin with ¼ tablespoon butter. Set aside.
Place 2 tablespoons of butter in a small microwave safe bowl. Heat in microwave until just melted. Set aside.
Whisk together the sugar, flour, and cocoa powder in a small bowl until thoroughly combined.
Add the melted butter, egg yolk, and vanilla. Stir with a spoon or a rubber spatula to combine. Do not overmix.
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.
Remove from the oven and let cool for 5 minutes before enjoying.
Notes
Expert Tips
Choose Quality Chocolate: Choose well-known brands like Ghirardelli, Guittard, or Scharffen Berger. Budget-friendly options include Trader Joe's and Whole Foods' 365 chocolate chips.
Select the Right Ramekin: Stick to a 10-ounce ramekin for optimal baking. Using a smaller or larger size could alter the baking time and texture.
Avoid Overmixing: Mixing the batter too much can lead to a cake-like texture. Aim for a just-combined batter for a fudgy result.
Watch the Baking Time: Keep an eye on the clock to prevent overbaking, which results in a dry brownie. Remember, it will continue to firm up as it cools.