1. Cook the potatoes in a saucepan of boiling salted water for 20 minutes, or until easily pierced with the tip of a knife. Drain well, and leave to cool and dry out, then peel and mash.
2. Gently mix the flour, cornflour, salt, egg, cheese, pepper and nutmeg together with the potato in a large bowl to form a dough (be careful not to overwork it as this will make it glutinous).
Preheat the oven to 200°C (400°F). Line two baking trays with baking paper.
3. Lay the dough out onto a floured surface and, using your hands, roll it out into a long cylinder approximately 60 × 10 cm (24 × 4 in). Flatten off the top of the cylinder with your palms, then cut the cylinder in half lengthways. Cut each half on a 45° angle into 5 cm (2 in) wide diamonds, placing the diamonds on the prepared baking trays as you cut them and cleaning the knife blade between cuts to prevent it sticking to the dough. You should end up with 25–30 whistles.
4. Sprinkle the whistles with a little flour, dot with 50 g (1¾ oz) of the butter and bake for 30 minutes, until browning on the edges and slightly puffed in appearance.
5. Melt the remaining butter in a large frying pan over a low heat, add the leek and cook for 5 minutes, or until soft. Add the mushrooms and sauté for another minute, then add the whistles and gently mix together. Season well with salt and pepper, then pour over the cream and gently mix again. Remove from the heat, cover with foil and leave to sit for 2 minutes, then transfer to a serving platter or individual plates. Serve topped with chopped chives.
Note:
The cheese in the sauce here isn’t traditional, but I find it adds extra flavour and helps bind everything together; this sauce can also be served separately with the whistles straight from the oven, if you like. Alternatively, the whistles can be covered in the sauce before being baked, but I prefer the method here as it gives them a better consistency.
Recipe and photography from Baltic by Simon Bajada (Hardie Grant, RRP $50)