1. Prepare Pans:

• Line four 8-inch round pans thoroughly with plastic wrap, ensuring enough overhang to easily lift the layers out later.
• Place the lined pans in the freezer to chill for at least 15 minutes.

2. Make and Freeze Crust Layer:

• In a small bowl, mix together the chocolate cookie crumbs and the melted butter until combined.
• Press this mixture firmly and evenly into the bottom of one of the chilled, lined pans.
• Freeze for 15 minutes to set the crust.
• Remove the pan from the freezer. Spread the softened vanilla ice cream evenly on top of the crust, smoothing the top.
• Cover tightly with plastic wrap and return to the freezer.

3. Prepare Other Ice Cream Layers:

• Working with one flavor at a time, spread the softened birthday cake ice cream into a second chilled, lined pan, smoothing the top. Cover tightly and return to the freezer.
• Spread the softened chocolate ice cream into a third chilled, lined pan, smoothing the top. Cover tightly and return to the freezer.
• (The fourth pan will be used for the brownie layer if needed, or kept spare).

4. Initial Freeze:

• Freeze all three ice cream layers (vanilla/crust, birthday cake, chocolate) for at least 4 hours, or until completely firm.

5. Assemble the Cake:

• Ensure your 8-inch round brownie layer is ready (cooled if homemade).
• Working quickly to prevent melting: Unwrap the vanilla ice cream layer (with crust on the bottom) and place it crust-down onto your final serving plate or cake board.
• Unwrap the chocolate ice cream layer and carefully place it on top of the vanilla layer. Press gently.
• Place the brownie layer on top of the chocolate ice cream. Press firmly to adhere.
• Unwrap the birthday cake ice cream layer and carefully place it on top of the brownie layer.
• Wrap the entire stacked cake tightly with plastic wrap. Return it immediately to the freezer to firm up completely (at least 1-2 hours, or longer).

6. Make Stabilized Whipped Cream Topping (Inferred Steps):

• Bloom Gelatine: Sprinkle powdered gelatine over 2 tablespoons of cold water (or soften sheet gelatine in cold water per package directions). Let sit for 5-10 minutes until bloomed/softened.
• Dissolve Gelatine: Gently warm the bloomed gelatine mixture (e.g., microwave for 5-10 seconds) or gently heat the squeezed-out sheet gelatine with 1-2 tablespoons of the cream, just until dissolved and liquid. Do not boil. Let cool slightly but remain liquid.
• Whip Cream: In a chilled bowl, whip the remaining cold heavy cream and the cane sugar with an electric mixer until soft peaks form.
• Stabilize: With the mixer on low speed, slowly drizzle the slightly cooled, liquid gelatine mixture into the whipped cream. Increase speed to medium-high and whip until stiff peaks form.

7. Frost and Decorate (Inferred Steps):

• Remove the firmly frozen stacked cake from the freezer and unwrap it.
• Quickly frost the top and sides of the cake with the stabilized whipped cream. You can make it smooth or create decorative swirls.
• Decorate the cake with the mini meringues and mini chocolate chips as desired (e.g., around the border, scattered on top).
• Return the finished cake to the freezer for at least 30 minutes to set the frosting before slicing and serving.