Mont Blanc (Chestnut Cream Dessert)

Method

1. 1Heat the oven to 110 °C (conventional, top and bottom heat). Using an 8 cm glass or cutter and a pencil, draw 6 circles on a sheet of baking paper, 3 cm apart, then turn the paper over onto a baking tray of about 30 × 40 cm so the pencil side faces down. The circles should still show through the paper. A low oven dries the meringue without colouring it.
2. 2Separate 4 large eggs and put the whites (130 g) in a large, clean bowl with no grease in it and no trace of yolk; keep the yolks for another dish. Fat or yolk stops the whites from foaming. Beat with a hand mixer on medium speed for 2 to 3 minutes, until foamy and just holding soft peaks. Switch to high and add the 240 g of caster sugar a tablespoon at a time, then keep beating for about 8 minutes. The meringue is ready when it is thick and glossy, holds stiff peaks that stand up, stays put when you tip the bowl, and a little rubbed between your fingers no longer feels gritty. Adding the sugar slowly keeps the foam stable.
3. 3Spoon or pipe the meringue into the 6 circles, about 62 g each, so each round fills its circle and stands about 2.5 cm high. With the back of a spoon, press a shallow hollow into the middle of each one. The hollow is where the cream dome will sit.
4. 4Bake for 1 hour 30 minutes at 110 °C. Then switch the oven off and leave the meringues inside with the door closed for another hour. They are done when they are dry and firm, white to the palest cream colour, lift off the paper cleanly and sound hollow when you tap them. A thoroughly dried meringue stays crisp under the cream.
5. 5While the meringues bake, make the chestnut paste. Put the 200 g of cooked, peeled chestnuts (vacuum-packed or from a jar), the 250 g of sweetened chestnut spread (crème de marrons) and 1 tbsp of dark rum in a food processor. Blend for 2 to 3 minutes, scraping down the sides, until the paste is completely smooth with no lumps, soft but able to hold its shape on a spoon. Any lump will block the ricer later. Cover and chill until you assemble.
6. 6Once the meringues have cooled, pour 300 ml of cold heavy cream (at least 35% fat) into a second large bowl and add 20 g of the icing sugar and 1 tsp of vanilla extract. Whip for about 4 minutes, until the cream holds firm peaks and the surface is still smooth. Stop there: whipped any further, it turns grainy and heads towards butter. Firm cream is what keeps the dome standing under the chestnut strands.
7. 7Set each meringue on a dessert plate. Spoon or pipe a dome of cream onto it, about 7 cm across, leaving a thin rim of meringue showing. Fill a potato ricer with chestnut paste and press it over the dome, moving round and turning the plate, until the cream is completely hidden under brown strands but the white edge of the meringue still shows. If you have no ricer, use a piping bag with a 3 to 4 mm plain tip. Dust the desserts with the remaining 5 g of icing sugar through a fine sieve.
8. 8Chill the Mont Blancs for at least 30 minutes, then serve them the same day; the meringue slowly softens under the cream. Keep them in the fridge until serving, and put any leftovers back within 2 hours, because whipped cream is perishable.