Preheat the oven to 200°C fan-forced. Cut six rectangles, approximately 13cm x 7cm, from the puff pastry. You'll have a little pastry left over; save it for later or use it to make mini mille-feuille. 

Sprinkle the rectangles with raw sugar and place on a lined baking tray. Bake for 15 minutes, until puffed but not completely golden. Place another sheet of baking paper over the pastry and gently press down with a smaller baking tray to deflate it. Return to the oven with the tray still on top for another 15 minutes, or until cooked through, crisp and golden. Set aside to cool completely. 

While the pastry is cooking, cut the cheeks off the mangoes and score the flesh in a small criss-cross pattern. Scoop the cubes out with a large spoon and place them in a bowl. Save the seeds for a snack later. Zest the lime over the mango, squeeze in half the lime juice, and toss to coat. Set aside. 

Whip together the cream, mascarpone, vanilla, powdered sugar and salt, adjusting the salt to your preference. If you'd like to omit the salt completely, that's fine. Whip until medium peaks form, then refrigerate until you're ready to assemble. 

To assemble, place ½ tsp of the mascarpone cream on a serving plate, then place one rectangle of pastry on top to secure it. Spoon on a 1cm layer of cream, spreading it to the edges, then add the mango. Top with another piece of pastry, then repeat with cream and mango. Finish with a final rectangle of pastry and dust with icing sugar. Prepare the second mille-feuille the same way. 

Assemble right before serving at the table with a bundle of spoons, a bunch of friends, and no fear of getting a little messy. Dig in and enjoy.