Preheat your oven to 375 degrees. Grease a 9 inch spring form pan and set aside.
In a large bowl, whisk together 1/2 cup vegetable oil and 1 cup sugar until fully combined. Whisk in 1 tsp vanilla extract and 2 large eggs.
In a medium bowl whisk together 1/4 tsp baking powder, 1/3 cup cocoa powder, 1/4 tsp salt, and 1/2 cup all purpose flour. Whisk the dry ingredients into the wet ingredients. Stir in the peanut butter chips. Pour the batter into the prepared pan.
Bake for 15 minutes at 375 degrees. Cool for 10 minutes in the pan, run a knife around the edge of the pan and then remove the side of the pan. Remove the bottom of the pan and allow to cool completely.
Preheat your oven to 350 degrees.
In a large bowl, mix together 2 cups flour, 1/2 tsp baking soda, 1/2 tsp baking powder, and 1/4 tsp salt.
In a large stand mixer, cream together 1 cup butter and 1 cup brown sugar and 1/2 cup granulated sugar until light and fluffy, about three minutes. Then beat in the 1 cup peanut butter until combined, scrapping down the sides as needed. Beat in the 2 eggs one at a time, and then beat in the 2 tsps vanilla.
With the mixer on low, slowly add the flour until just combined.
Scrape down the sides of the mixer and then using a spatula gently fold in the 1 cup chocolate chips.
Spray a 9 inch spring form pan with cooking spray. Add the batter to the pan.
Bake on the middle rack for 19 to 24 minutes or until the edges of the cake begin to turn golden brown. (The center will still have a slight wiggle to it.)
Allow the cake to cool in the pan for twenty minutes. Gently run a knife between the cake and the edge of the pan, then remove the side of the pan. Cool completely. Carefully, using a serrated knife, level the cake so the top is flat.
Preheat your oven to 350 degrees. Spray a 9 inch spring form pan with cooking spray and set aside.
In a large bowl, whisk together the 1 cup sugar, 3/4 cups + 2 TBSPs flour, 1/3 cup cocoa powder, 3/4 tsp baking powder, 3/4 tsp baking soda, and 1/2 tsp salt.
Then mix in the 1 egg, 3/4 cup skim milk, 1/4 cup vegetable oil, 1 tsp vanilla extract and 1/4 cup water. Pour the batter into the prepared pan.
Bake for 25 - 27 minutes or until a toothpick stuck in the center of the pan comes out clean.
Cool for 10 minutes in the pan, run a knife around the edge of the pan and then remove the side of the pan. Remove the bottom of the pan and allow to cool completely.
To make the peanut butter frosting beat together the butter and peanut butter until combined in a stand mixer or with a hand held mixer.
Slowly add in the powdered sugar and then the milk, followed by the vanilla extract. If not smooth and creamy, add a tiny bit more milk.
To make the chocolate frosting beat the butter in a stand mixer or a large bowl with a hand held mixer.
Add in the melted chocolate, cocoa powder, and vanilla extract.
Slowly add in the powdered sugar one cup at a time. Then add in the heavy cream.
Store in an airtight container until you are ready to use.
To assemble the cake, first place the brownie layer on a large plate, cake stand, or 10 inch cake circle
. Add a small amount of the peanut butter frosting, adding more as needed to create a nice even 1/4 layer.
Add the cookie layer, another layer of the peanut butter frosting and finally the chocolate cake layer.
Add a thin layer of the chocolate butter cream frosting. Add another, thicker layer of chocolate frosting.
Pipe on decorative peanut butter frosting. Add mini chips ahoy to the top. Add some crumbled chips ahoy to around the base of the cake.
Cut and serve!