• I recommend preparing all the layers a full day (or more) before assembly. Especially the ice cream layer. Each layer should be fully frozen before assembled.

For the cake layer

• Preheat your oven to 330 degrees, check for accurate temp with an oven thermometer.
• In a bowl combine buttermilk, imitation vanilla extract, and room temp eggs. Mix to break up the eggs and combine.
• Add flour, salt, baking powder, and sugar to the bowl of your mixer.
• Add the softened butter and mix with your paddle attachment on the lowest setting on your stand mixer until it looks like coarse sand, about 1 minute.
• With your mixer on low, add around half of your wet ingredients. You really just want to add enough liquid so that everything is a little wet without forming a dough texture, it should resemble cake batter. Then turn it to medium and let it mix for 2 minutes. Set a timer and do not go over. This helps develop the structure of the cake, without over mixing.
• Scrape your bowl after the 2 minutes. With your mixer on low add the rest of your wet ingredients. Mix just until totally combined. About 15 seconds.
• Prepare your pan by spraying the sides and lining the bottom with parchment paper.
• Pour all of the batter into the pan and smooth the batter so it’s flat in the pan, then cover with aluminum foil.
• Bake until done about 75 min. When the cake is done the sides will start to slightly pull away from the pan and a toothpick inserted in the center will come out clean.
• Place on cooling rack, carefully remove foil.
• Let the cake cool for about 15 min or until the pan is cool enough to touch and remove it from the pan to cool completely.
• Once cake is totally cool wrap it in plastic wrap and freeze it to prepare it for assembly.

Cookie Dough Layer

• To make the flour safe to eat, microwave it for 1 minute and let it cool.
• Put the softened butter and sugars into a bowl and work them together. 
• Once the flour is cool, add the flour and salt to the mixture and work it together with a spoon or spatula.
• Add the milk and vanilla and combine until smooth.
• Fold in the chocolate chips with a spatula.
• Prepare an 8 inch cake pan by lining the bottom with parchment paper.
• Reserve 1/3 cup of cookie dough for decorating in an airtight container in the refrigerator.
• Put the rest of the cookie dough in the prepared 8 in cake pan and press it flat and evenly to make the layer. You can put parchment on top of it and use a smaller cake pan to help flatten it.
• Cover the pan with plastic wrap an freeze until ready to use.

To prepare the ice cream layer

• Leave the ice cream container on the counter to soften 15-30 minutes depending on the temperature in your home. You want it softened, not liquid.
• Thoroughly line an 8 inch cake pan with plastic wrap so all the sides are covered, and the corners don't have empty space between the plastic and pan.
• Put the entire container of softened ice cream into the pan. Smooth it flat using an offset spatula. Put plastic on top. Using another 8 inch cake pan, flatten the ice cream and make sure it is level. Freeze until ready to assemble.

For the Buttercream

• Put the softened butter in the bowl of your mixer. Fit the mixer with your paddle attachment.
• Beat the butter on medium for 2-3 minutes until it's smooth and lighter in color.
• With the mixer on low add the imitation vanilla and salt.
• Turn off the mixer and add the powdered sugar. Slowly let that start incorporating. I prefer to turn the mixer on and off because of the dust cloud it creates. Once it's not making a lot of dust I turn it on to the lowest setting.
• Add the cream and let the mixture run for a few minutes until well combined and smooth. Cover the mixture while not using.

To Assemble

• Do not remove components from the freezer until you are about to use them. Work quickly when possible. Make sure there is a flat cleared surface in the freezer for the cake.
• On a cake board, put a small dollop of buttercream and put the cake top side down on the board.
• Remove the frozen cookie dough layer from the pan by running a knife around the edge. Place it directly on top of the cake layer with no buttercream between the layers.
• Remove the plastic from the ice cream layer and place that directly onto the cookie dough layer. I placed mine upside-down so the top was smoothest.
• Crumb coat the cake with a thin layer of the buttercream.* Because it is so cold the buttercream will begin to harden quickly so you will want to work quickly. The most important part here is to make sure all of the ice cream layer has buttercream on it before it begins to melt at all.
• Once it is crumb coated, place the cake on a flat surface in the freezer for at least 10 minutes. If things seemed melty you may want to leave it for 30 minutes.
• Cover the rest of the cake in buttercream and smooth with a bench scraper until it is evenly coated and smooth. Place it back in the freezer.
• To decorate it like mine, fill a piping bag fitted with a piping tip with the left over buttercream. I used ateco tip 865, wilton 4B is similar.
• Make a scallop design around the top edge of the cake. Break up bits of the reserved cookie dough to place on top.
• Store the cake in the freezer until ready to serve.