Step 1: Preheat and Prepare the Pastry

Start by preheating your oven to 200°C (or 180°C for fan-forced). Line an oven tray with baking paper and place your partially thawed puff pastry rectangles on the tray. To ensure your pastry remains flat and cooks evenly, cover the pastry with a sheet of baking paper and then weigh it down with a second tray. This will prevent the pastry from puffing up too much as it bakes, giving you crisp, even rectangles.

Step 2: Bake the Pastry

Bake the pastry in the preheated oven for about 18 minutes or until the pastry rectangles are golden and crispy. The edges should be slightly browned, and the center should remain firm. Once baked, remove the pastry from the oven and set it aside to cool completely. The crispness of the pastry will provide the perfect contrast to the creamy layers and moist fruitcake, giving each bite a delightful crunch.

Step 3: Prepare the Fruitcake

While the pastry is cooling, cut your store-bought fruitcake into 6 slices that are the same size as the ice cream slices you will be using. If you have extra fruitcake left over, you can store it for later use or serve it as a snack. The rich, dark fruitcake will add a moist, dense layer to your mille-feuille, balancing out the sweetness of the ice cream and fruit.

Step 4: Assemble the Mille-Feuille

Now comes the fun part—assembling the layers! Line a freezer-proof tray with baking paper to prevent the mille-feuille from sticking. Take one of the pastry rectangles and place it on the prepared tray. Spread 1 tablespoon of raspberry conserve (or any fruit preserve you prefer) evenly over the pastry. Starting from one short end, arrange a slice of ice cream upright on the pastry, followed by a slice of fruitcake. Then add another ice cream slice, another fruitcake slice, and finish with a final slice of ice cream. Repeat this layering process two more times to cover the pastry entirely.

Step 5: Top with the Second Pastry Layer

Take the second pastry rectangle and spread 1 tablespoon of raspberry conserve over the surface. Place this pastry on top of the layers, conserve-side down, to form a sandwich. This will hold everything together and help set the layers as the mille-feuille freezes. Pop the tray in the freezer for about 2 hours, or until the ice cream has refrozen and the mille-feuille is firm enough to handle.

Step 6: Prepare the Whipped Cream and Berries

While the mille-feuille is freezing, prepare the whipped cream. Using a hand mixer or stand mixer, whip the thickened cream until soft peaks form. For an extra burst of flavor, fold in 1 tablespoon of raspberry conserve through the whipped cream. This will give the cream a slight raspberry flavor that complements the fruity layers of the mille-feuille beautifully.

Once the mille-feuille is ready to be served, spoon the whipped cream on top of the pastry layers. Drizzle any remaining raspberry conserve over the top, then scatter fresh berries—raspberries, strawberries, and blueberries—generously over the whipped cream. The berries not only add a burst of color but also provide a fresh, tangy contrast to the creamy and sweet layers below.

Step 7: Serve Immediately

Once everything is beautifully layered and topped with fresh berries, serve the mille-feuille immediately. The combination of crunchy pastry, creamy ice cream, and fruity layers will make every bite a festive and indulgent treat.