Preheat oven 176℃/350℉. Spray a 9-13-inch baking tray with oil spray, wipe over with a paper towel, and set aside.
Whisk flour, cocoa powder, sweetener, sugar and baking powder until combined.
In a separate bowl, whisk the butter/oil, yoghurt, egg, vanilla and milk until combined.
Pour into the dry ingredients and mix well with a wooden spoon (being careful not to over beat).
The batter should be smooth, creamy and lump free.
Fold through crushed cookie pieces.
Pour batter into baking tray and bake for 25 - 30 minutes, or until a toothpick inserted into the centre comes out clean. (my toothpick came out a little 'dirty' when I took them out after 30 minutes, and they were beautiful, moist and fudge-y).
While brownies are baking, make creamy frosting!
Frosting:
Whisk frosting ingredients in a separate bowl until lump free.
When brownies are done, remove from oven and allow to cool for 5 minutes before frosting
Once cooled, frost with cream frosting and top with extra crushed cookies if you wish.
Gently cut into 20 bars.
Notes
You can use either Oreo cookies or a healthier Oreo cookies substitute! Or omit them altogether!For more of a decadent dessert type of bar...sprinkle some chocolate chips over the top! Because there's never such thing as too much chocolate!