Rinse the potatoes and cook with the skin on in salted water for 20-25 minutes. Drain, let cool slightly and peel. Mash the warm potatoes a little, let them evaporate for 20 minutes, then press them through the potato press. Chop chestnuts finely. Add the egg yolk, starch, chestnuts and flour to the potato mixture. Knead everything into a smooth dough, season with salt, pepper and nutmeg.
Place the Tyrolean bacon slices on a baking tray lined with baking paper. Bake in a preheated oven at 180 degrees (fan oven 160 degrees) on the second rack from the bottom for about 10 minutes until crispy. After the baking time, remove the bacon from the oven and drain on kitchen paper.
Divide potato dough into 3 portions. Form each portion into a roll about 40 cm long on a little flour. Cut each roll into 15-20 equal pieces. First shape the pieces into balls, then into tapered Schupfnudeln. Spread Schupfnudeln on a baking tray sprinkled with starch.
Clean and halve the Brussels sprouts and cook in salted water for 4-5 minutes. Drain and immediately place in ice-cold water, then drain. Remove the pomegranate seeds: To do this, hold the pomegranate over a plate with the cut side facing down and hit the peel with a wooden spoon until all the seeds have been loosened, collecting the separating membranes. Finely dice the onion and garlic.
Heat clarified butter in a very large pan. Fry the onion, garlic and Brussels sprouts over medium heat for about 6 minutes and season with salt and pepper. Pour in white wine and let it boil down. Pour in the cream and reduce by half. If necessary, rinse chervil, shake dry and pick off the fine leaves. Finely grate the Parmesan.
Bring plenty of salted water to the boil in a large pot. Add Schupfnudeln in 2 portions, heat until just below the boiling point and remove the pot from the heat. As soon as the Schupfnudeln rise, let it sit for another 2-3 minutes. Remove with a slotted spoon and drain well.
Add Schupfnudeln to the sauce and toss, serve with Brussels sprouts. Scatter pomegranate seeds and Parmesan on top, place slices of bacon on top, sprinkle with chervil and serve.