Cookie Dough:
Using a hand or stand mixer, cream together the butter and sugars using the paddle attachment.
Add in the milk and vanilla and mix until combined.
Mix in the flour and salt, then fold in the chocolate chips.
Scoop (15) 1 1/2-tbsp sized balls and flatten slightly. Place the cookie dough “patties” on a plate lined with wax paper and refrigerate along with the leftover dough.
Cookie Dough Cake:
Preheat the oven to 350°F (175°C). Prepare three 8-inch round cake pans by coating them with non-stick spray and lining the bottoms with parchment paper.
In a small bowl, whisk together the flour, baking powder, and salt. Set aside.
In a measuring glass, mix the milk and vanilla. Set aside.
In a large bowl using a hand or stand mixer, cream together the butter and sugar with the whisk attachment on medium-high speed until light and fluffy, about 3-5 minutes.
Turn the speed to medium and add in the eggs one at a time, ensuring each is fully incorporated before adding the next. Mix in the yogurt.
Alternate between adding the flour mixture and the milk mixture, beginning and ending with the flour (three additions of flour, two of milk). Fold in the mini chocolate chips.
Divide the batter evenly among the prepared cake pans. Push down 5 cookie dough “patties” into each pan, then cover with the remaining batter.
Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean. Rotate the cakes halfway through to ensure even baking.
Let the cakes cool in the pans for 20 minutes before turning them out onto a cooling rack. Remove the parchment paper and refrigerate the cakes for at least an hour to prevent breakage while frosting.
Cookie Dough Buttercream:
Cream together the butter and brown sugar.
Gradually mix in the powdered sugar and flour, adding the milk between each addition.
Mix in the salt and vanilla. Do not add the chocolate chips yet.
Assemble:
Spread an even layer of buttercream between each cake layer, using a heaping scoop of frosting for each.
Stack the cake layers, then refrigerate the naked cake for 20 minutes to set.
Mix the mini chocolate chips into the remaining buttercream, then frost the outside of the cake.
Chocolate Ganache:
Place the chopped chocolate in a bowl.
Heat the heavy cream in the microwave for 1 minute, or until it begins to bubble.
Pour the hot cream over the chocolate and whisk until smooth. Add 2-3 tsp of vegetable oil to thin the ganache for drizzling.
Pour the ganache over the center of the cake, using a small offset spatula to spread it to the edges, allowing it to drip down the sides.
Crumble the remaining cookie dough over the top of the cake.