Make the cookie dough by beating softened butter with light brown sugar and granulated sugar until light and fluffy. Add milk and vanilla extract, mixing until combined. Stir in salt and flour until a dough forms, then mix in chocolate chips. Scoop into 18 small cookie dough balls, flatten slightly, and refrigerate.

Preheat oven to 350°F (175°C). Grease and line two 8-inch round cake pans with parchment paper.

In a bowl, whisk together cocoa powder, flour, granulated sugar, salt, baking powder, and baking soda.

Add vanilla extract, oil, eggs, and milk to the dry ingredients. Pour in hot water and mix until smooth.

Divide batter evenly between the two pans and gently push 9 cookie dough pieces into each pan, ensuring they are covered with cake batter. Bake for 20-26 minutes, until a toothpick inserted in the middle comes out clean.

Let the cakes cool in the pans for 20 minutes before removing and then cool completely on a wire rack.

Prepare the frosting by heat treating the all-purpose flour. Combine softened butter with vanilla extract, granulated sugar, light brown sugar, and 1 tablespoon of milk. Mix in heat-treated flour and salt, adding more milk if needed until desired consistency is reached. Stir in chocolate chips.

Assemble the cake by placing one chocolate cake layer on a serving plate, spreading frosting on top, and placing the second layer on top. Frost the top and sides as desired, and crumble any remaining cookie dough on top for decoration.