Take a 6-inch round cake springform pan and grease it with butter on the bottom and the sides.

Prepare the crust by grinding the Oreo cookies into powder. You could either use a food processor or just put the cookies inside a zip pouch and use a rolling pin to crush it into dust. Once the cookies are crushed, add melted butter and mix it together. Place the mixture on the greased pan and press it firmly at the bottom to form a uniform layer.

Once done, place the pan in the refrigerator while you prepare the milk chocolate mousse.

Pour water into a small saucepan. Drizzle the gelatin powder and give it a sir. Keep it aside for 5 minutes for the gelatin to bloom (as the gelatin absorbs the liquid the granules enlarge). This step is crucial for the gelatin to dissolve properly.

While the gelatin blooms, melt the milk chocolate chips. Place a saucepan filled with water on high heat and bring it to a boil. Lower the heat to medium and place a glass or stainless-steel mixing bowl on top of the pan. Drop the milk chocolate chips on the bowl along with the milk. Using a whisk, stir until the chocolate melts completely.

Once the chocolate has melted, place the small saucepan that has the gelatin on medium heat and let the gelatin dissolves completely. It will take about a minute. Pour the dissolved gelatin into the melted chocolate and whisk it to mix everything together.

Next, using an electric whisk or a hand whisk, whip the heavy whipping cream until it is stiff. Pour the melted chocolate, that was mixed with dissolved gelatin, into the whipped cream and whisk once again to mix everything together. Pour the mixture in the cake pan, layer it evenly and leave it in the refrigerator while you prepare the next layer of chocolate mousse.

To prepare the next two layers of chocolate mousse, follow the exact same procedure as you did for the milk chocolate. Let the gelatin bloom, melt the chocolate chips, dissolve the gelatin, mix the dissolved gelatin to the melted chocolate, whip the cream, mix the chocolate to the whipped cream and whip again. Then, layer it on the top of the previous chocolate mousse layer.

After the third layer, leave the cake inside the refrigerator for at least 4 hours or overnight to set completely.

Once you are ready to serve to the cake, take the cake pan out of the refrigerator and keep it aside for 5 minutes. Take a clean knife and run it along the edges of the cake. It should release very easily. Detach the ring carefully. Next, run the knife around the bottom of the pan to release the Oreo crust and carefully transfer the cake to a serving plate or a cake stand.

To prepare the chocolate ganache, place a saucepan filled with water on high heat and bring it to a boil. Lower the heat to medium and place a glass or stainless-steel mixing bowl on top of the pan. Drop the milk chocolate chips in the bowl along with the butter and milk. Using a whisk, stir until the chocolate melts completely.

To prepare the chocolate soil, just grind the Oreo cookies into dust, the same way that you did for preparing the crust.

Drizzle the chocolate ganache on top of the cake. I added some white sprinkles too, followed by the chocolate soil and some fresh mint. You could also add some fresh berries, if you like.