Ingredients :
For the crunchy biscuits:
20 Oreo cookies or other chocolate sandwich cookies
3 tablespoons unsalted butter, melted
4 ounces semi-sweet chocolate chips
1 ounce of coconut oil

For the hot fudge sauce:
1 cup heavy cream
2 tablespoons unsalted butter
1/2 cup granulated sugar
Pinch of salt
6 ounces semi-sweet chocolate chips
1/2 cup cocoa powder

For the ice cream cake and frosting:
1 1/2 quart store-bought or homemade vanilla ice cream
Cooking spray
1 1/2 quart store-bought or homemade chocolate ice cream
2 cups of heavy cream
1 cup icing sugar
1 teaspoon of pure vanilla extract
Pinch of salt
Sprinkles, for decoration, optional

Steps to do it:
Make the crunchy cookies:
Gather the ingredients.

Place a rack in the center of the oven and heat to 350 F.

Ingredients to Make Cookie Crumble Cake Topping
Pulse the cookies several times in a food processor to break them into small pieces. Add the butter and continue to pulse until you have coarse crumbs. You don’t want the crumbs to be too fine like sand, but small enough to form little clusters.

Chocolate biscuits and pulsed butter in a food processor
Spread cookie crumbs on a large rimmed baking sheet in a single layer. Bake until the cookies are dry and set into clumps, about 10 minutes.

A baking sheet with cookie crumbs
Meanwhile, melt the chocolate and coconut oil in a double boiler until melted and smooth.

Melted chocolate and coconut mixed in a large bowl over a saucepan of water
Pour the chocolate mixture over the cookie crumbs and fold together until combined. Spread into an even layer. Refrigerate while you prepare the hot fudge sauce.

Make the hot fondant:
Gather the ingredients.
Ingredients to Make Hot Fudge Sauce
Combine heavy cream, butter, sugar and salt in a medium saucepan. Bring to a boil over medium heat, whisking until the sugar dissolves, about 1 minute. Let simmer for 1 more minute. Remove from the heat and add the chocolate. Continue whisking until the chocolate melts and the mixture is smooth.

Add the cocoa powder and whisk until no lumps remain. Return the pan to medium-low heat and cook, stirring continuously, until the sauce is glossy and smooth, about 1 minute.
Let the mixture cool slightly, then transfer it to the refrigerator to cool completely. The sauce will continue to thicken as it cools.

Assemble the cake and decorate:
Gather the ingredients.
About 20 minutes before you are ready to assemble the cake, prepare the vanilla ice cream to soften. Spray a 9-inch springform pan with cooking spray. Alternatively, line the cake pan with plastic wrap.
An 8-inch cake pan lined with plastic wrap

Scrape vanilla ice cream into prepared pan. Spread the ice cream in an even layer using an offset spatula. Freeze for 20 minutes. Meanwhile, take the chocolate ice cream out of the freezer to soften it.

Break cooled cookie mixture into small pieces. Sprinkle about half over the vanilla ice cream layer. Reserve the remaining crunchy biscuits for garnish, if desired.

Pour about 3/4 of the fudge sauce over the crunchy cookies. Spread in an even layer with an offset spatula. Freeze for 10 minutes. Reserve remaining fudge sauce to serve

Scrape the chocolate ice cream over the fudge sauce. Carefully spread the ice cream into an even layer using an offset spatula (you may have some chocolate ice cream left over). Make sure you don’t press too hard so as not to disturb the other layers.

Freeze until cake is completely set, 2 to 3 hours.

Chocolate ice cream is added on top of the fudge layer
Unmold the cake by inverting it onto a plate or cardboard round. Wrap a warm kitchen towel around the cake pan until the cake loosens and falls apart, about 30 seconds.

Ice cream cake spilled on a plate
Remove the pan and smooth the edges using an offset spatula run under hot water. Use the offset spatula to help remove the top from the cake pan. Smooth the top. Return to the freezer while you make the icing.

Combine the heavy cream, powdered sugar, vanilla and salt in the bowl of a stand mixer fitted with the whisk attachment. Whisk on medium-high speed until stiff peaks form.

A bowl of whipped cream with firm peaks
Working quickly, frost the top and sides of the cake as desired. You can use Wilton #21 or Ateco #844 tips to pipe a border around the top and bottom of the cake. If the cake becomes soft during frosting, return it to the freezer for about 10 minutes and continue.

Frosted ice cream cake with whipped cream topping and pique rosettes
Top with sprinkles and any remaining crunchy cookies, if desired. If serving with remaining hot sauce, microwave hot sauce for 10 seconds to soften. Slice and enjoy.