Cream the Butter and Sugar: In a stand mixer, beat 1 cup of cold cubed unsalted butter with 1 cup of brown sugar for 2-3 minutes. Add eggs one at a time, beating well after each addition.
Combine Dry Ingredients: In a separate bowl, mix 3 cups of flour, 1 teaspoon of cornstarch, 1 teaspoon of baking soda, and 1 teaspoon of salt. Gradually fold this dry mixture into the wet ingredients until a dough forms.
Add Festive Mix-Ins: Fold in 1 1/2 cups of chopped Christmas Oreo cookies, 1 cup of white chocolate chips, and 1/3 cup of festive sprinkles. These add-ins create a delightful twist, perfect for giant Oreo Christmas cookies.
Chill and Bake: Refrigerate the cookie dough for 30 minutes. Roll into large cookie dough balls (yielding approximately 12 cookies). Bake at 415°F for 10-12 minutes.
Rest and Enjoy: Allow the giant Oreo Christmas cookies to rest for 30 minutes to achieve a soft and gooey texture.