Mix the fennel, carrot, mushrooms and shallot in a wide, ovenproof dish (approx. 2.5 l), season. Rinse the trout with cold water inside and out, pat dry, season inside and out and place on top of the vegetables, top with knobs of butter. Add the wine.
Bake for approx. 25 mins. in the centre of an oven preheated to 200°C. Remove from the oven, transfer the vegetables to a bowl and allow to cool slightly. Mix in the oil and spinach. Fillet the trout, arrange on the warm salad and sprinkle with almonds.