You can either boil the chestnuts yourself or you can use store-bought pre-boiled, or steamed chestnuts to speed things up. To boil the chestnuts: wash 1 cup of chestnuts, then in a large pot, put them to boil with plenty of water.Boil for 50 minutes, then drain, and peel them with a paring knife. Remove the outer shell and the thin brown skin under the outer shell. Don't worry if they break, we'll blend them in a second.
Blend all the ingredients together until you have a thick cream, almost like a hummus.You can make the cream more or less smooth based on your preference. We like it smooth but with a grainy texture. Set aside.Note: depending on the chestnuts, you might need to add one or two tablespoons of extra soy milk to get the blender going.
For the pasta dish
In a large pot, bring the water to boil, then salt it with coarse sea salt and add the spaghetti. Give it a stir. Cook as instructed on the package, minus 1 minute. Save two cups of pasta cooking water before draining the pasta.
While the pasta boils, add the oil to a non stick pan. When the oil is warm, add the clove of garlic and chopped mushrooms.Cook the mushrooms on medium heat for 8 minutes, season with salt, then add 4 to 5 spoonfuls of chestnut pesto and 1 cup of pasta cooking water.
Stir to dissolve the pesto and turn it into a sauce. Add more pasta water if necessary.
Add the spaghetti to the pan and stir well. Add some chopped parsley and finish cooking the pasta until creamy and al dente. If the sauce is too thick, add more pasta water.
Portion into serving plates, sprinkle with some more parsley, serve and eat immediately.
*you can either boil the chestnuts yourself, then peel them. Or you can use pre-boiled, or steamed chestnuts to speed things up.