1. For the hollandaise sauce, place 100g of the butter into a small saucepan and melt slowly over a gentle heat. When melted, remove from the heat and set aside.
2. Place the egg yolks into a bowl over a pan of gently simmering water (bain-marie) and beat until pale and thickened. Add the water, lemon juice, salt to the egg yolks and beat vigorously for another minute.
3. Take of the heat and add the remaining butter cubes of butter to the egg mixture in the bowl and whisk for 2-3 minutes or until the mixture thickens. (using an electric whisk where possible makes the process easier).
4. Slowly pour in the melted butter, whisking constantly, until the sauce becomes silky and smooth. Season to taste with lemon juice and salt.
5. Cut mushrooms into thin slices and sautee in butter and garlic till cooked and lightly brown. Season lightly with salt.
6. Toast the brioche slices in a pan or under the grill till light brown. Be very careful as the brioche can burn very quickly.
7. Arrange the mushrooms and then steamed spinach on top of the muffins.
8.Place the poached eggs and pour the hollandaise sauce over the top.
9. Sprinkle some black pepper or cayenne pepper on top for an Asian twist.