Press the garlic cloves flat. Wash and clean the pumpkin and cut into thin slices. Put slices and garlic on a baking tray, season with coarse salt and drizzle with olive oil. Chop chestnuts finely.
Wash the thyme, shake dry and chop the leaves of 4 stems finely. Mix butter, chestnuts, breadcrumbs and thyme. Season to taste with salt and pepper. Wash the chicken, dab dry.
Season with salt and pepper. Heat the oil in a pan, fry the chicken fillets on both sides, remove. Deglaze frying pan with approx. 4 tbsp. water. Roast the pumpkin in a preheated oven (electric cooker: 200 °C/ circulating air: 175 °C/ gas: level 3) for about 20 minutes.
Spread the chestnut mixture on the fillets. Add the chicken fillets with the roasting set to the pumpkin after 5-10 minutes. Add 2 stems of thyme and cook for the last 5 minutes. Cut the chicken fillets diagonally in half and arrange with the pumpkin slices.
Garnish with thyme.