Beef Stroganoff
Beef Goulash
Beef in red wine/bourguignon
Beef brisket slow-cooked ragu, with any pasta
Beef curry & rice
All above can be cooked ahead and frozen, serve with either mash, baby potatoes, rice or noodles, & selection of veg.
Beef fillet steak - quickly pan fried, with M&S peppercorn sauce, baby boiled or baby roast potatoes, green beans, etc.
Pork tenderloin medallions, quickly pan-fried, serve with potatoes/veg, & one of M&S sauce pouches - Bramley apple & cider, or Creamy mushroom, are nice (don't tell her you bought them!
.
Pork Schnitzel with creamy cheesy mash & veg.
Gammon & egg, with potato wedges or chips, & peas.
Prawn curry & rice
Prawn Caesar salad topped with hard boiled egg & croutons, with a nice baguette.
Aubergine parmigiana with salad
Vegetarian Moussaka with Greek salad
Vegetarian mixed bean chilli with rice
Bacon & Leek quiche with salad
Steak & Mushroom pie with veg
Tray-baked Mediterranean roast vegetables with Feta cheese (aubergine/courgette/red onions/cherry tomatoes/mixed peppers/garlic) served with sliced baguette, brushed with olive oil/garlic and toasted in the oven.
Have a 'no cook' night and put out a grazing platter of cooked sliced meats, cheeses, pate, baguette, crackers, pickles, olives & chutney, etc.
Hope you can find something your niece enjoys from all the lovely suggestions posters have given you.