Cook the noodles in plenty of salted water until they are firm to the bite.
Finely dice the onions and slice the mushrooms.
Fry the onions in the oil over medium heat and add the mushrooms. Add the crushed garlic. Stir everything well and add the broth. Let it boil briefly and add the cayenne pepper. Stir in the crème fraîche.
Remove the pan from the heat and stir in the basil leaves. Season to taste with salt and pepper.
Drain the cooked pasta and serve mixed with the mushroom sauce.