Peel and clean carrots and celery and cut them into small cubes. Peel and finely dice the onion. Peel and chop the garlic.
Heat the oil in a pan. Fry the minced meat for about 5 minutes until crumbly, then add the diced vegetables, onion and garlic and fry for another 2-3 minutes. Stir in tomato paste, add stock and tomatoes.
Season with salt, pepper and paprika and simmer covered for about 15 minutes.
Cook the pasta in boiling salted water according to the instructions on the packet. Break the feta into pieces. Wash oregano, shake dry and chop the leaves of 4 stems into small pieces. Drain the noodles. Mix sauce, noodles and chopped oregano and season again.
Put the pasta in a greased casserole dish and sprinkle with feta. Bake the casserole in a preheated oven (electric oven: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for 10-15 minutes until the cheese is slightly browned.
Remove the casserole from the oven and garnish with the remaining oregano.