Vacherin

Method

1. Heat the oven to 100C (conventional, no fan if possible). Draw two 12 cm circles on a sheet of baking parchment, turn it pencil-side down and lay it on a baking tray. Wipe the bowl and whisk of a stand mixer with a little vinegar or lemon on kitchen paper so they are perfectly grease-free.
2. Put 1 egg white and a pinch of salt in the bowl and whisk on medium speed to soft, floppy peaks, about 2 minutes. Still whisking, add 65 g caster sugar a teaspoon at a time, taking a good 4-5 minutes in all, then whisk on high for 3 minutes more until the meringue is stiff, glossy and holds a straight point on the whisk; rub a little between your fingers — it should feel smooth, with no grains of sugar. Whisk in 0.25 tsp white wine vinegar.
3. Dab a little meringue under each corner of the parchment to glue it down. Using a palette knife, spread about half the meringue into one circle as an even disc 1 cm thick. Spoon the rest into a piping bag with a 1 cm star nozzle and pipe a single ring of touching rosettes around the line of the second circle — this is the collar of the vacherin.