Line two baking sheets with greaseproof paper. Make a stiff meringue in the usual way with the egg whites, cream of tartar and the sugar.
Use a piping bag and a plain 1cm nozzle pipe to make 24 rounds of meringue onto the baking paper sheets for the 'caps' of the mushrooms, and 24 oblonges approximately 4cm long for the 'stems' of the mushrooms.
Bake at 110*C for approximately 1 hour, turn off oven and leave the meringues to cool.
Melt the chocolate and copha together in a bowl over hot water. Carefully make a hole in the base of each mushroom cap for the stem. Spoon a little chocolate into each cap and place the stem into position. Leave on a cooling tray until the chocolate has hardened.
Just before serving, sift a little cocoa over the mushrooms to give them an earthy look.