Method

• 1.
  For the royal icing, in a stand mixer fitted with the whisk attachment, beat the egg whites until frothy. Add the icing sugar, 1 tablespoon at a time, until fully incorporated. Add the vanilla extract and salt, then mix until smooth. You are looking for a pipeable consistency. If the consistency is too runny, add a bit more icing sugar – a little at a time. If it’s too thick, add a little water – again, just a little at a time until you have reached the desired pipeable consistency. Fresh royal icing will need to be used within 3 days and stored in the refrigerator, or you can freeze it for up to 3 months.
• 2.
  Sift together the flour, ginger, cinnamon, bicarbonate of soda and salt in a medium bowl and set aside.
• 3.
  In a stand mixer fitted with the paddle attachment, beat the butter and sugar on medium speed until light and fluffy. Add the mayonnaise and continue mixing, making sure to scrape down the sides and bottom of the bowl from time to time. Add the eggs, one at a time, and continue mixing until fully incorporated. Slowly mix in the dry ingredients on a low speed. The batter will be soft but pliable.
• 4.
  Tip the dough onto the work surface and bring it together into a ball. Cover with clingfilm (plastic wrap) and chill in the refrigerator for 15 minutes.
• 5.
  If you can get hold of a mushroom cookie pan, roughly form pieces of the dough into mushroom shapes and place in the pan. Cook over a medium heat for 3 minutes, then flip it over and cook for another minute or so. Release and repeat process with the rest of the dough.
• 6.
  If you haven’t got a mushroom pan, preheat the oven to 200°C (180°C fan/400°F/Gas mark 6) and line two baking trays with baking paper.
• 7.
  Divide the dough in half. Shape one half of the dough into mushroom caps – about 2.5cm (1in) in diameter – by making a flattened ball and using your thumb to hollow out the middle. Shape the other half of the dough into stem shapes, about 2.5cm (1in) long. Place on the baking trays (you will need to work in batches) and bake for 10–12 minutes, rotating the pans halfway through. Cool on a wire rack and repeat the process until all the dough is used up.
• 8.
  Meanwhile, put the royal icing into a medium bowl and thin it out slightly with a little water to get a dipping consistency. Cover and set aside.
• 9.
  When cool, you can decorate your mushrooms. If they were baked in a cookie pan, they will be ready to decorate. Dip the stem ends in the royal icing and shake the excess off. Let dry for 15 minutes or so (egg cartons are very useful for this). The bottoms will still be a little wet, so dip them into the poppy seeds at this point, rolling the base around a little, then leave to dry completely.
• 10.
  If you are shaping the cookies by hand, first stick the caps to the stems using a little melted chocolate. Once cooled, follow the previous step.
• 11.
  While the cookies are drying, make the chocolate ganache by placing the chopped chocolate in a medium bowl. Heat the cream in a small saucepan over a medium heat until just about to simmer, then pour it over the chocolate, let it stand for 2–3 minutes, then stir with a silicon spatula until the chocolate is fully melted.
• 12.
  Dip the mushroom caps into the chocolate ganache and leave to dry in the egg carton between the triangles so that the cap hardly touches the surface.