Preheat your oven to 350 degrees F (180 degrees C).
In a food processor pulse the Cookies (350 gram) into powder.
Transfer mixture into a bowl and add Milk (370 gram) and Baking Powder (1 teaspoon). Whisk all the ingredients together.
Transfer batter into an 8-inch cake pan, lined with parchment paper.
Bake in a preheated oven at 350 degrees F (180 degrees C) for about 40 minutes or until a toothpick inserted in the center comes out dry.
Dust the top with some powdered sugar if you fancy. Slice it up and enjoy!