Preheat oven to 350 and grease an 8" cast iron skillet
In a medium mixing bowl add the ground flaxseed and 3 tbsp of water and let set for 3-5 minutes to gel
Add the sugar and butter into the bowl and stir till combined
Add flour, baking powder, salt, baking soda, and vanilla into the butter mixture and mix until well combined and a dough is formed
In a large ziplock bag place the oreo cookies and crush until until you still have a few decent size chocolate cookie chunks
Fold the cookies into the dough
Place the dough into the greased cast iron skillet and press down to make sure it is an even layer. Place in the oven for about 25 min until just starting to get golden brown
Serve warm for a goey cookie or cold for a more set chewier cookie.