Prepare the Base: Place the chocolate biscuits in a food processor and pulse until they form fine crumbs. If you don't have a food processor, pop them in a sturdy plastic bag and bash with a rolling pin. Pour the crumbs into a bowl and stir in the 125g of melted butter until the mixture resembles wet sand.

Form the Crust: Tip the buttery crumbs into a 23cm (9-inch) round pie dish or springform tin. Use the back of a spoon or the base of a glass to press the crumbs firmly and evenly across the bottom and up the sides of the dish.

Chill the Base: Place the pie dish in the refrigerator to chill for at least 30 minutes. This step is crucial for ensuring the base is firm and doesn't fall apart when you add the filling.

Whip the Cream: In a large, chilled bowl, pour in the 450ml of cold double cream. Using an electric hand mixer or a stand mixer, whip the cream until it forms stiff peaks. Be careful not to over-whip. Set aside.

Make the Cream Cheese Mixture: In a separate large bowl, beat the room-temperature cream cheese and sifted icing sugar together until completely smooth and creamy. This is where lumps can form, so take a minute to ensure it's silky. Beat in the peppermint extract and the food colouring, if you're using it.

Combine the Filling: Take a large spoonful of the whipped cream and stir it into the cream cheese mixture to loosen it up. Then, gently fold in the remaining whipped cream in two or three additions. I find that using a large metal spoon in a figure-of-eight motion helps to keep all the air in the mixture, resulting in a lighter mousse.

Fill and Chill: Spoon the peppermint filling into your chilled biscuit base and gently spread it out into an even layer with a spatula.

The Final Chill: Cover the pie loosely with cling film and place it in the refrigerator to set for a minimum of 6 hours, though overnight is even better. The pie needs this time to become firm enough to slice cleanly.

Decorate and Serve: Just before you're ready to serve, you can either top the pie with more whipped cream or serve it as is. Sprinkle the crushed candy canes and dark chocolate shavings over the top. Slice and serve immediately.