Ingredients
Method
- Prepare the pan: Flip the base of a 20 cm (8-inch) springform pan upside down. Lightly grease the base, lay a square of baking paper over it, and lock the ring back on with the paper overhanging the sides to help lift the cake out later.
- Preheat the oven: Preheat to 180°C / 350°F (or 160°C fan).
- Make the custard — heat the milk: In a large saucepan, warm the milk, vanilla, and about half the sugar over medium-high heat. Stir occasionally until the sugar dissolves and the milk is just below boiling (small bubbles at the edge).
- Mix the yolks: In a medium bowl, whisk the egg yolks with the remaining sugar until combined. Add the cornstarch and whisk until smooth and lump-free.
- Temper the eggs: Slowly pour the hot milk into the yolk mixture in a thin stream, whisking constantly to prevent scrambling.
- Cook the custard: Return the mixture to the saucepan and cook over medium-low, stirring constantly. After 3–5 minutes it will begin to thicken. When it becomes steamy and large slow bubbles form at the bottom, continue whisking for 45 seconds to fully cook and stabilize the custard.
- Add the chocolate: Remove from heat, add the chopped dark chocolate, and stir until melted and glossy. Transfer to a bowl and press cling film directly onto the surface to prevent a skin forming. Set aside while you make the base.
- Make the biscuit base: Place the Oreos in a food processor and blitz to fine crumbs. Add the melted butter and pulse until the mixture resembles wet sand.
- Pour the crumbs into the prepared springform pan and press down firmly with the back of a flat-bottomed cup or glass to form an even, compact layer.
- Assemble: Whisk the custard briefly to loosen, then pour it gently over the Oreo base. Smooth the top with a spatula.
- Bake: Bake in the preheated oven for 60 minutes, rotating the pan after about 45 minutes for even cooking. The centre should still wobble slightly when done.
- Cool: Leave the cake to cool in the pan on the counter for 3 hours.
- Chill: Cover and refrigerate for at least 12 hours (overnight) so the custard firms to perfect slicing texture.
- Serve: Release the springform, slide the cake off the base using the paper overhang, slice while cold (warm the knife under hot water for cleaner cuts), and serve at room temperature with Chantilly cream and berries if desired.
Notes
Use quality dark chocolate (65%–75%) for best flavor. If custard looks slightly lumpy after cooking, whisk vigorously off the heat—it usually smooths out. Slice with a warm knife for neat pieces. Store refrigerated up to 4 days; freeze individual slices for up to 1 month.