Wash the potatoes thoroughly, dab dry and place on a baking tray. Cut them crosswise, sprinkle them all around with oil and season with salt and pepper. Cook in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for about 1 hour. Clean and wash the leek, cut it in half lengthwise and cut it into strips. Peel and wash the carrots, quarter them lengthwise and cut into pieces.
Clean, wash and halve the mushrooms. Melt 1 tablespoon butter in a pot, add prepared vegetables and fry until translucent. Take out vegetables. Melt 2 tbsp. butter in a pot, dust with flour and sauté. Deglaze with stock and cream, bring to the boil and simmer for about 5 minutes. Season to taste with salt and pepper, fold in vegetables. Take potatoes out of the oven and let them cool down a little. Grate cheese.
Deglaze with stock and cream, bring to the boil and simmer for about 5 minutes. Season to taste with salt and pepper, fold in vegetables. Take potatoes out of the oven and let them cool down a little. Grate cheese. Press potatoes a little bit apart and put them into a suitable casserole dish. Pour sauce and vegetables over the potatoes, sprinkle with cheese and bake in the oven at the same temperature for 12-15 minutes
Waiting time approx. 15 minutes