Gnocchi with mushroom and red wine sauce, garnished with Parmesan

1. In a bowl, cover the mushrooms with boiling water.
2. Let swell for about 15 minutes.
3. Drain the mushrooms and coarsely chop.
4. Set aside.
5. In a saucepan, cover the potatoes with cold salted water.
6. Bring to a boil.
7. Cook, covered, for about 20 minutes or until soft.
8. Meanwhile, in another saucepan, heat the butter over medium-high heat.
9. Brown the shallots and mushrooms for 3 to 4 minutes, stirring frequently.
10. Add the garlic and cook for another minute, stirring continuously.
11. Moisten with red wine.
12. Reduce by half.
13. Add the demi-glace.
14. Season with salt and pepper.
15. Simmer for about 10 minutes or until desired consistency (see note).
16. Set aside and keep warm.
17. At the end of the cooking, drain the potatoes. Mash with a potato masher.
18. Place in a large bowl.
19. Add the egg yolk, flour and salt.
20. Stir well, and knead until ingredients are evenly distributed.
21. Shape 4 balls of dough.
22. On a floured countertop, roll the first ball into a sausage, about 2 cm (3/4 in.) in diameter.
23. Cut into 2 to 3 cm (1 in.) chunks.
24. Roll the gnocchi on the back of a fork, and place on a cooking sheet lined with parchment paper. Repeat the previous steps until all dough is used.
25. Cook the gnocchi in salted boiling water, a small quantity at a time, for 3 to 4 minutes. (The gnocchi are cooked once they float on the surface.)
26. Warm up the gnocchi in the sauce for about 2 minutes.
27. Garnish with chopped parsley and Parmesan shavings.
28. Serve immediately.

Note: Depending on the choice of demi-glace, the sauce's consistency may vary. If needed, add a bit of cornstarch dissolved in a bit of warm water.