Preheat oven to 350°F. Line two large baking sheets with parchment paper and set aside. Chop 4 of the Oreos and the mini chocolate chip cookies, then set aside. (Leave 10 of the Oreos whole to stuff in the cookies.)
In a large bowl, beat the butter and sugars together until light and fluffy with an electric mixer (about 1-2 minutes). Mix in the egg, food coloring, and vanilla extract.
Add in the dry ingredients - flour, salt, and baking soda - and mix until just combined (don't over-mix). Fold in the chocolate chips, chopped Oreos, and chopped mini chocolate chip cookies.
Scoop 10 heaping tablespoons of cookie dough onto each baking sheet. They should be fairly big (these are monster sized cookies). Press a whole Oreo cookie slightly into the dough, then add more dough on top to cover the Oreo completely. The cookies will weigh around 3 oz once assembled.
Bake the cookies one tray at a time in the preheated oven for 8-10 minutes, until edges and top look set. Let cool on the baking sheet for 10 minutes, then transfer to a cooling rack to finish cooling.Use a sharp knife to cut them in half to reveal the Oreo cookie inside.