1 Preheat the oven to 110°C, gas mark ¼ and line 2 solid baking sheets with baking parchment. Fit a large piping bag with a 1.5cm plain nozzle.
2 Place the egg whites into a medium heatproof glass or ceramic bowl, add the sugar, cream of tartar and a pinch of salt. Set the bowl over a pan of simmering water, not touching the surface. Whisk for at least 5 minutes or until the sugar has completely dissolved, the mixture is white and warm to the touch. Remove from the heat and continue whisking for 3 minutes or until thick, glossy and white and will stand in stiff peaks.
3 Spoon just over half the meringue into the piping bag and pipe about 25-30 domes in assorted sizes onto the parchment, to make the mushroom caps. Flatten the pointed peaks with a wet fingertip. Dip a clean dry pastry brush into the red food colouring and use a finger to flick it over half of the mushrooms.
4 Scoop the remaining meringue into the piping bag and on another baking sheet pipe 25-30 upright cone shapes in assorted sizes – these will be the stalks of the mushrooms. Bake the caps and stalks for 1 hour, swapping the trays around halfway through. Remove from the oven and leave to cool completely.
5 Melt the chocolate in a heatproof bowl over a pan of simmering water or in the microwave. Stir until smooth and remove from the heat. Using a wooden skewer, make a 3mm hole in the middle of the underside of each mushroom cap. Dip the flat underside of each one in melted chocolate and place back on the parchment.
6 Place 1 mushroom cap on top of each stalk – you may need to carefully knock the spikey top off the stalks first – positioning the top of the stalk into the hole in the underside of the caps. Dust the top of the plain mushrooms lightly with cocoa. Sprinkle a tray or serving platter with more cocoa and arrange the mushrooms on top to serve.
Recipe and image courtesy of Waitrose & Partners