Make Mousse Layers and Ganache

1. Prepare a 9-inch springform pan by lining the sides with parchment paper or an acetate collar that sticks about an inch above the sides of the pan. Set aside.
2. Make the mousse by mixing the cream cheese and sugar together in a large mixer bowl until smooth.
3. Add the milk and mix until smooth. Set cream cheese mixture aside and make whipped cream.
4. Add the heavy whipping cream, vanilla extract and powdered sugar to a large mixer bowl and whip on high speed until stiff peaks form.
5. Carefully fold 1/3 of the whipped cream into the cream cheese mixture until combined. Add the remaining whipped cream and fold together until well combined.
6. Divide the mousse into two bowls. You’ll want twice the amount in one bowl as the other. You should have about 2 1/3 cups in one bowl and the rest in another.
7. Add the Nutella to the bowl with the larger amount of mousse and gently fold to combine. Set aside.
8. Add the Biscoff to the smaller amount and fold to combine. Set aside.
9. Put the chocolate chips for the ganache in a medium-sized heat proof bowl. Heat the heavy whipping cream for the ganache in the microwave or in a small saucepan until it comes to a boil, then pour over the chocolate chips. Allow to sit for about 2-3 minutes, then whisk until smooth. Set aside to cool a bit and thicken.

Assemble Trifle

1. Place a single layer of chocolate wafer cookies into the bottom of the prepared pan.
2. Top the cookies with half of the Nutella mousse and spread into an even layer.
3.  Add another layer of chocolate wafer cookies on top of the Nutella mixture.
4. Top the cookies with half of the ganache mixture and spread into an even layer.
5. Spread the Biscoff mousse into an even layer on top of the chocolate ganache.
6. Add another layer of chocolate wafer cookies on top of the Biscoff mousse, then add the remaining ganache and spread into an even layer.
7. Top the ganache with the remaining Nutella mousse and spread into an even layer.
8. Refrigerate cake until firm, 4-5 hours.

Finish Off Trifle

1. Once firm, remove icebox cake from pan.
2. Make the chocolate whipped cream topping by adding heavy whipping cream, powdered sugar and cocoa to a large mixer bowl. Whip on high speed until stiff peaks form.
3. Scoop the chocolate whipped cream into a piping bag fitted with a piping tip (I used Ateco tip 847). Pipe the whipped cream around the top edge of the cake, then drizzle with chocolate sauce.
4. Finish off cake with Biscoff cookies and Ferrero Rocher, if desired.
5. Refrigerate cake until ready to serve. Best if eaten within 3-4 days.