Butter a medium-sized Savarin mold (Turk's head mold). Have ready enough fillets from brook trout of a length equal to the height of the mold. Each trout gives two fillets. If the trout be salmon-colored, alternate the fillets with fillets from halibut or similar white fish. Trim all the fillets straight on each side, press them against the sides of the mold, aslant, following the pattern of the mold. At the top, where the pattern is wider, slip a slice of truffle between each two fillets, letting one side of the slice go under one fillet and over the other, sprinkle a few drops of melted butter on each and let chill to hold in place. If there be space, have two rows of truffles completely around the mold. Also let the ends of the fillets lie over the edge of the mold both at the top and at the bottom. At the bottom they will extend up on to the tube found in a Savarin mold. When the butter has chilled and the lining of the mold is in perfect condition, fill it with a mousseline forcemeat made of lobster. Turn the ends of the fillets over the forcemeat and make the mixture perfectly smooth on the bottom. Poach on paper surrounded with water until firm in the center. Remove from the water and let stand a few moments to contract a little. Unmold on a serving dish. Fill the open space in the center with shrimps made hot in Bechamel sauce to which a little lobster butter has been added. Truffles in slices may be mixed through the sauce.