Baked sea bass with fennel and porcini mushroom

By Theo Randall From Saturday Kitchen Ingredients 70g/2½oz unsalted butter, plus extra for greasing 2 sea bass fillets, about 175g/6oz each 1 fennel bulb, core removed, sliced and blanched 1 fresh porcini mushroom, trimmed and sliced 2 fresh thyme sprigs 100ml/3½fl oz dry …