- 1kg button mushrooms (to make 240g mushroom purée)
- 250g / 5 large eggs
- 240g sugar
- 40g glucose
- 100g water
- 230g flour
- 9g baking powder
- 100g unsalted butter, browned
To make the mushroom purée, trim off the fibrous ends of the mushroom stems. Place in a vacuum bag and seal on the highest setting. Cook en sous vide in a large pot of water at 91˚C for 1 hour, until tender. Transfer to a blender and process until silky smooth then pass through a fine sieve.
In an electric bench-top mixer, whisk together the eggs, sugar and glucose on high until ribbons stage.
In a separate bowl mix together the mushroom purée with the water then fold into the egg mixture.
Sift together the flour and baking powder onto the mixture, fold together then stir in the browned butter. Pour into a baking dish lined with baking paper, cover with tinfoil and steam for 10-15 minutes until the cake feels spongy to touch.