Cook the dumplings in boiling water for about 7 minutes, drain and allow to drain. Clean, wash and cut the peppers into pieces. Peel and chop onion. Heat oil in a pan. Fry the vegetables in it.
Add the tomatoes and chop a little. Season with salt, pepper and thyme. Cut cabanossi into slices, add and stir without stirring. Fill the vegetable pan and dumplings into a greased casserole dish. Grate the cheese and sprinkle over the top.
Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 8-10 minutes. Serve garnished with thyme.