Preheat oven to 350 degrees F ,and spray two 9 inch round cake pans with Pam baking spray. Set aside.
In a large mixing bowl, beat all cake ingredients together until fully combined.
Divide batter between the two prepared baking pans. Bake in preheated oven for 25-35 minutes ,or until a toothpick inserted in the center comes out clean.
Cool completely. Cut the domes off the top of the cake. Use a cake slicer to slice each cake in half. You should end up with a total of 4 rounds.
For the Frosting
In a large bowl, combine brown sugar, powdered sugar, and butter.
Add the flour and vanilla in, stir until combined.
Slowly add the milk until the consistency is achieved.
Fold the mini chocolate chips into the frosting.
For the Chocolate Ganache
In a small saucepan, heat up the heavy whipping cream until steaming.
While heavy whipping cream is heating up, place chocolate chips into a heat-proof bowl.
Once the heavy whipping cream is heated, pour over the chocolate chips.
Allow to sit for 1 minute before whisking until smooth.
Pour ganache into a squeeze bottle.
Putting It All Together
Place the first cake layer onto a serving plate. Scoop ~1 cup of cookie dough frosting onto the first layer and smooth out evenly.
Repeat steps with remaining cake layers.
Pour ganache onto the center of the to layer, and smooth until even
Using the squeeze bottle, create a drizzle effect around the top of the cake by squeezing some ganache over the side and allowing it to drip down.
Allow to sit for 10 minutes to allow ganache to harden.
Pipe dollops of frosting onto the top of the cake. Top with cookies.
Notes
Ingredient Notes:
Cake Mix: I like Betty Crocker's Triple Chocolate Fudge best.
Milk: I always use whole milk.
Flour: Measure your flour by spooning it into the measuring cup. I also suggest toasting your flour for around 8-10 minutes at 350 degrees F to kill any potentially harmful bacteria.
Mini Chocolate Chips: I prefer mini here, so they're not so large and hard to bite into.
Tips
Don't Overmix Your Batter: Mix until just combined, or the gluten will overdevelop, leading to a tough, dense cake.
Grease Pans: For easy removal, line your cake pans with parchment paper and spray them with nonstick spray. I like to use Pam baking spray as it includes flour to further help prevent things from sticking.
Don't overbake: Cake is done when a toothpick inserted comes out with just a few moist crumbs.
Use a Cake Leveler: This helps give you flat layers for easy stacking. If you don't have one, you can also use a knife or bake your cake with cake strips to prevent this.
Get perfect drips by using a squeeze bottle and dripping onto a chilled cake.
Place a dollop of frosting on your cake plate or cake board to prevent it from moving around.