Baked pasta with minced meat and béchamel sauce

Meats and vegetables:

500g (about 1.1 lb) ground beef
1 onion,
chopped 1 carrot, diced
2 cloves garlic, minced
100g (about 1 cup) mushrooms, sliced
​​1 bell pepper, diced
50g (about 3 tbsp) tomato paste
Salt and black pepper, to taste
1 tsp paprika
1 tsp mixed herbs (optional)
1/4 tsp nutmeg
Toppings:

Spring onions, chopped
Chopped parsley Dill
(optional)
Instructions:

Cook the pasta:
Boil water in a large saucepan. Add salt and a little oil. Cook the Ditali Rigati pasta for 7 minutes. Drain and set aside.
Prepare the béchamel sauce:
In a saucepan, melt the butter over medium heat. Add the flour and stir continuously for 2 minutes.
Gradually pour in the milk, whisking until the sauce thickens. Season with salt, black pepper and nutmeg.

Stir in shredded mozzarella until melted. Set aside.
Prepare meat and vegetables:
Heat oil in a skillet over medium heat. Add ground meat and cook until browned.
Add onion, carrot and garlic. Cook until vegetables are tender.
Stir in mushrooms, bell pepper and tomato paste. Season with salt, black pepper, paprika and mixed herbs. Cook for a few more minutes.