1. Wash, dry, and prick the potatoes with a fork in several places and place them on a baking sheet lined with parchment paper.
2. Preheat the oven to 220 °C / 425 °F.
3. Bake them in the oven for about 1 hour, until the flesh is completely cooked.
4. Remove the potatoes from the oven and cut them in half lengthwise.
5. Scoop out the flesh, place it in a medium-sized bowl, and set aside the hollowed-out skins on the baking sheet.
6. Roughly mash the potatoes with 40 g of butter, cream, gorgonzola, 1 teaspoon of salt, and a good amount of freshly ground pepper, and set aside.
7. Butter the potato skins with the remaining 10 g of butter.
8. Season the inside with salt and bake them in the oven for 8 minutes until they become crispy.
9. Remove the baking sheet from the oven and set it aside.
10. Slice the mushrooms, then mince the garlic and parsley.
11. Heat butter and olive oil in a pan and sauté the mushrooms until they are golden brown.
12. Add the garlic and parsley.
13. Remove the pan from the heat.
14. Add the mushrooms to the mashed potatoes and place this mixture in the potato skins.
15. Place the stuffed potatoes back in the oven and bake them until the top becomes golden and crispy.
16. Remove the stuffed potatoes from the oven, sprinkle them with walnuts and parsley, if desired, and serve.
17. Tip: For a touch of freshness, add thin slices of fresh pear just before serving.