Cook the potatoes in boiling water for about 20 minutes. In the meantime peel and finely dice the onion. Heat the fat in a pot and fry the onion until transparent. Add the frozen peas, steam for about 1 minute, cover and leave to stand on the switched off hotplate.
Quarter the peppers, clean, wash, pat dry and cut into cubes. Dice the ham. Wash thyme, dab dry and, except for a few stems for garnishing, pluck leaves from the stems.
Separate eggs. Mix egg yolks with quark, milk and semolina. Stir in parmesan except for something to sprinkle, and thyme. Season well with salt and pepper. Potatoes, drain, quench, peel and slice.
Mix the potatoes, peas (except some for sprinkling), paprika and ham. Beat the egg whites until stiff and fold into the curd mixture. Grease an oven dish (length: 30 cm; width: 19 cm; height: 4 cm) and sprinkle with breadcrumbs.
Layer the potato mixture and curd mixture alternately in the casserole dish. Sprinkle with remaining peas and parmesan. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 45 minutes.
Cover at the end of the baking time if necessary. Garnish with thyme.