I made this dish recently, and it turned out very good. Here's how I made it:

You need:

• 250g dried macaroni
• 200g grated mozzarella cheese
• 1 large filet of white fish
• 2 handfuls of frozen chopped spinach
• 2 tbsp chopped dried tomatoes
• 1 lemon
• 2 tbsp butter
• 2 tbsp flour
• 1 handful of grated parmesan
• 2 cups milk
• 1 tsp ground nutmeg

Cooking:

• Cook the macaroni in salted water according to instructions.
• Meanwhile, melt the butter in a saucepan.
• When the butter has melted, add the flour and stir until even.
• Add the milk little by little, while stirring to prevent lumps.
• Add the parmesan, nutmeg to the sauce. Season with salt & pepper.
• Bring the sauce to boil, while keeping an eye on it and stirring regularly.
• Place a frying pan on high heat and add some olive oil.
• Once hot, break the fish fillet into pieces and fry them for a few minutes. Add the spinach and dried tomatoes. Season with salt & pepper.
• Grate the zest of the lemon into the frying pan and stir.
• Drain the cooked pasta and transfer to an ovenproof dish.
• Pour over the sauce and the contents of the frying pan. Stir everything around.
• Spread the grated mozzarella across the pasta and sauce and place in an oven at 200 degrees celcius, until the cheese is golden.
• Eat!