Heat your oven to 200°C/Fan 180°C/Gas 6. Halve the butternut squash. Scoop out the seeds. Peel it. Chop the squash into chunks around 1 cm across.
Pop the squash in a bowl. Add 1 tsp olive oil. Season. Toss to mix the squash, oil and seasoning together. Spread the squash out on a non-stick baking tray. Roast for 30 mins till the squash is tender and a little charred.
Slice the skin off the oranges, as close to the flesh as possible. Using a small knife, slice the oranges into segments over a bowl to catch any juice, leaving behind the thin membranes. Pop the orange segments in a separate bowl. Squeeze any juice left in the membranes into the bowl of juice.
Peel and finely slice the onion. Add to the orange segments. Rinse the watercress. Pat dry with kitchen paper. Pick out any thick stalks. Add the watercress to the orange segments and onion.
Add 1 tsp olive oil to the orange juice with a pinch of salt and pepper. Whisk together to make a dressing. Put to one side.
Place the trout fillets, skin-side-down, on a baking tray lined with baking parchment. Sprinkle 1 tsp ras el hanut over each fillet and gently rub it in to the fish.
Pop the trout in the oven on the top shelf. Bake for 10 mins till the trout is opaque and cooked through. Add the roast squash to the orange salad. Pour over the dressing. Toss to mix together. Divide between two plates. Serve with the trout fillets.