Photograph: Martin Poole
Line an 18cm-deep loose-bottomed cake tin with baking paper so that it is at least 10cm above the top of the tin.
Put the flour, salt, yeast, milk, eggs, yolks, vanilla, maple syrup, coffee essence and butter in a large bowl and stir well to combine. Keep mixing the dough using a wooden spoon for 10 minutes (or, if using an electric mixer fitted with a dough hook, for 5 minutes). The dough will be very sticky, almost like cake batter. This is what gives the panettone its wonderful spongy texture.
Tip the dough into the prepared cake tin and lay a tea towel over the top. Leave in a warm place for 1-1½ hours, or until the mixture has risen almost to the top of the tin.
Preheat the oven to 200°C, fan 180°C, gas 6. Brush the top of the panettone with the egg wash, then make a cross in the top with a very sharp knife and sprinkle with the sugar crystals.
Bake in the oven for 50 minutes-1 hour, or until the bread is well risen and lifts out of the tin easily, and a skewer inserted into the thickest part comes out clean. Remove the panettone from the oven and leave to cool in the tin.