Crush the Oreos: Place 300g of the Oreo biscuits (keeping the remaining 100g for the topping) in a large ziplock bag. Use a rolling pin to crush them until you have coarse crumbs with some small chunks remaining. You want a texture similar to wet sand with a few pea-sized bits for crunch. Set aside 100g of these crumbs for the topping later.

Make the base: In a medium bowl, combine the remaining 200g of crushed Oreo crumbs with the 100g of melted butter. Stir with a fork until every crumb is coated and the mixture feels like damp, dark sand. Press this firmly into the bottom of a 9x13 inch baking dish using the back of a measuring cup or your fingers. The base should feel compact and solid, not loose. Place in the fridge to set while you prepare the filling.

Prepare the pudding: In a large bowl, whisk together the 500ml milk and both packets of instant vanilla pudding mix. Whisk vigorously for 2 minutes until the mixture thickens and becomes glossy. You'll notice it transform from a thin liquid to a thick, wobbly pudding that holds its shape when you lift the whisk. Set aside to firm up for 5 minutes.

Whip the cream: In a separate large, chilled bowl, pour the 300ml double cream. Add the 50g icing sugar and 1 tsp vanilla extract. Using an electric hand mixer, beat on medium-high speed until soft peaks form. You'll know it's ready when the cream leaves soft, billowy trails on the surface and holds its shape when you lift the beaters, but is still silky and not stiff.

Make the cream cheese layer: In another large bowl, beat the 250g softened cream cheese with the 100g caster sugar and a pinch of salt until smooth and completely lump-free. Scrape down the sides of the bowl with a spatula. The mixture should be pale, fluffy, and smell sweet and tangy. Fold in the prepared vanilla pudding until fully combined. The mixture will be thick and creamy, like a very rich custard.

Fold in the whipped cream: Gently fold the whipped cream into the cream cheese and pudding mixture. Use a rubber spatula and a folding motion — cut down through the centre, scrape along the bottom, and bring up the side. Do this until no white streaks remain. The final mixture should be light, airy, and pale beige in colour, with a mousse-like texture.

Assemble the layers: Remove the baking dish from the fridge. Spread half of the creamy filling evenly over the Oreo base, smoothing the top with an offset spatula. It should look like a thick, even blanket. Scatter half of the reserved 100g crushed Oreo crumbs over the filling. Spread the remaining half of the creamy filling on top, again smoothing it out. Finally, sprinkle the remaining crushed Oreo crumbs and the 100g of whole Oreo biscuits you set aside over the top. Press them in very lightly so they stick.

Chill and set: Cover the dish tightly with aluminium foil and place it in the fridge for at least 4 hours, but overnight is much better. The dessert needs this time to firm up so you can slice it cleanly. When ready, it should feel firm to the touch and hold its shape when you cut into it, with defined layers visible.