Preheat the oven to 350°F (177°C) and spray a 6 inch round cake pan with nonstick spray and then place a round piece of parchment paper on the bottom for easy removal.
Add the package of cookies to a food processor and process until the cookies are ground into a fine flour.
Add the ground up cookies to a large bowl.
Add the baking powder and whisk until mixed through.
Heat the milk up for 20 seconds in the microwave until it's lukewarm.
Add the milk to the cookies and use a whisk to mix until a smooth batter forms.
Pour the batter into the pan and smooth out the top.
Bake on the center rack for 30-35 minutes, until a toothpick comes out completely clean from the center.
Cool 30 minutes in the pan and then carefully turn it out onto a plate and cool another 30 minutes to an hour in the fridge.
If wanting to add cookie crumbles to the top, add them while the cake is still in the pan and warm, so they stick.
