First thing...cut the 12 Oreos into 4.
Next - cream the sugars, butter, eggs, and the vanilla together.
While that's mixing, add all the dry ingredients together and mix well.
Add in the dry ingredients. Mix thoroughly.
Add in two-thirds of the M&Ms and 8 of the chopped Oreos. Mix on the lowest setting you have.
Then, spoon out all the mixture into a well buttered 9x13 pan.
Top the giant tray of cookies with the remaining M&Ms and Oreos.
Bake at 350 degrees for 23-25 minutes. Keep an eye out...once the edges start to brown they're done. The middle cookies will be so soft and chewy - they are the best ones!
Cut the cookies into squares and serve.