Preheat your oven to 350°F (175°C) and line a large baking sheet with parchment paper.

In a medium mixing bowl, cream together softened butter, brown sugar, and granulated sugar until smooth and fluffy for about 2-3 minutes.

Mix in one egg and 1 teaspoon of vanilla extract until thoroughly incorporated.

In a separate bowl, whisk together flour, corn starch, baking soda, and salt, then gradually add this to the wet ingredients.

Fold in the chocolate chips and Halloween sprinkles until evenly distributed.

Using a large cookie scoop (about 1/4 cup), flatten the dough slightly, place an Oreo in the center, and wrap the dough around the cookie.

Place the stuffed dough on the baking sheet and bake for about 10 minutes until slightly underdone.

Sprinkle extra chocolate chips on top and let the cookies cool for about 5 minutes before transferring to a cooling rack.