1. Prepare the Brownie Layers:

Preheat the oven to 350°F (175°C). Grease and line two 9-inch round cake pans with parchment paper.
In a large mixing bowl, whisk together the melted butter and sugar until fully combined.
Add the eggs one at a time, whisking well after each addition. Stir in the vanilla extract.
Sift in the flour, cocoa powder, and salt, and mix until just combined.
Divide the batter evenly between the two prepared pans and smooth it out into an even layer.
Bake for 20-25 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
Let the brownie layers cool completely in the pans.
2. Make the Cookie Dough Layer:

In a mixing bowl, cream together the softened butter, brown sugar, and granulated sugar until light and fluffy.
Add the milk and vanilla extract, mixing until well combined.
Stir in the flour and salt until fully incorporated, then fold in the mini chocolate chips.
Once the brownie layers are cool, spread the cookie dough evenly over one of the brownie layers.
3. Prepare the Chocolate Ganache:

In a heatproof bowl, combine the chocolate chips and heavy cream. Microwave in 30-second intervals, stirring between each, until the mixture is smooth and glossy. Let the ganache cool slightly before using.
4. Assemble the Cake:

Place the second brownie layer on top of the cookie dough layer.
Pour the chocolate ganache over the top of the cake, allowing it to drip down the sides for a beautiful finish.
5. Serve:

Allow the ganache to set for at least 30 minutes before slicing. Serve with a cold glass of milk or a scoop of vanilla ice cream for the ultimate treat.