In a stainless steel bowl, whisk the egg yolks, lemon juice, salt, hot sauce, and water, together. Set the bowl over a pot of simmering water. Whisk the mixture until pale yellow in color and frothy. Slowly whisk in the melted butter, 1 tablespoon at a time, until all the butter is incorporated and the sauce is thick. Fold in the Sauteed mushrooms and reseason if necessary. Place a cake in the center of a plate. Lay the poached egg on top of the cake. Spoon the Hollandaise over the egg and around the sides. Garnish with the caviar, fried spinach, chives and peppers.