Set a pan over medium heat and add butter or olive oil. Soften the onion and garlic until fragrant and translucent.

Add the spinach and kale, letting them wilt down completely. Season well with salt and pepper.

Stir in the Parmesan and cream cheese and cook until the mix is thick and creamy. Most of the moisture should be gone.

Add a teaspoon of nutmeg, then set aside to cool completely.

Lay one sheet of puff pastry on a lined baking tray. Place the trout fillet in the centre, skin side down.

Spread the cooled spinach mixture evenly over the fish.

Brush a little water around the pastry edges, then lay the second sheet on top. Press the edges together, trim away any excess, and crimp all the way round with a fork or your fingers to seal.

Brush with beaten egg yolk, then lightly score the top in a crosshatch or diagonal pattern for decoration. Make two steam holes to keep the pastry crisp.

Bake at 200°C (fan 180°C) for about 25–30 minutes, or until the pastry is deeply golden and crisp.

Let it rest for a few minutes before slicing.

Serve with roasted potatoes and a handful of peppery greens dressed simply with olive oil and lemon.