Cook the pasta according to the instructions on the packet in boiling salted water until it is firm to the bite. Peel and chop the onion. Wash basil, dab dry and chop leaves. Heat oil in a pot.
Sauté diced onions until translucent, mix with tomato paste. Dust with flour. Deglaze with tomato pulp, bring to the boil and season with salt, pepper and basil. Clean and wash spring onions and cut into rings.
Dice the ham. Grate cheese. Drain the pasta, let it drain. Mix ham and spring onion with the noodles. Put tomato sauce in a greased casserole dish. Wrap the noodles into nests with a fork and place them on the tomato sauce.
Sprinkle the cheese over the nests. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 15 minutes. Garnish with basil leaves.