If you were to chance upon some fresh wild mushrooms, by all means use them and leave out the dried porcini. I found some baguette-style brioches in the village shop but you could slice a large brioche loaf or split the small buns. I made this as a main course for supper but it would make a perfect first course although you may want to serve smaller slices of brioche.
- 20g dried porcini mushrooms
- For the hollandaise sauce
- 180g unsalted butter
- 3 large egg yolks
- 1 teaspoon Dijon mustard
- 1 teaspoon white wine vinegar
- Truffle salt to taste
- To finish the dish
- 35g butter
- 500g chestnut mushrooms, sliced
- 2 small garlic cloves, peeled and crushed
- 1 tablespoon thyme leaves
- 100g baby spinach leaves
- 2 large brioche baguettes or 4 slices from a large loaf (see intro)
- Put the porcini in a bowl and pour over enough boiling water to cover them. Leave to soak for 2-3 hours.
- For the hollandaise, melt the butter over a low heat. Put the egg yolks, mustard, vinegar and 1 tablespoon cold water in the small bowl of a food processor. Blend for about 1 minute then, with the motor running, very slowly pour in the hot melted butter. When the sauce is thick and glossy add a pinch or two of the truffle salt to taste. You can make the sauce about 1 hour in advance.
- Drain the soaked porcini mushrooms and finely chop. Melt the 35g butter in a sauté pan and add the chestnut mushrooms, chopped porcini and garlic. Sauté for about 5-6 minutes, stirring regularly. Add the thyme and spinach and cook for about 1-2 minutes until the spinach has wilted. Taste and season with salt and ground black pepper.
- Heat the grill to high and toast the brioche until golden. Spoon the mushroom and spinach mixture over the brioche. Drizzle over the hollandaise sauce and either glaze under the hot grill for 40-60 seconds or glaze with a blowtorch, until the hollandaise is golden. Serve immediately.