Bring a small pot of water to a boil. When the water is boiling add the cashews and boil for 15 to 20 minutes, or until they’re puffy and soft. Add the garlic cloves for the last two minutes of boiling to blanche.
Drain the cashews and garlic and rinse in cool water. Put them in a food processor or the blender and add the cashew milk, pumpkin, and seasonings and process until smooth and creamy. This should be a thick sauce, not runny.
FOR THE MANICOTTI
Bring a large pot of water to a boil. When the water is boiling, salt the water with approximately 2 tablespoon (30 g) of sea salt. This is optional but it yields a great pasta.
Boil the manicotti until al dente according to box instructions, and drain and spread the noodles out in a baking dish.
FOR THE MUSHROOM TOPPING
Heat a large skillet on medium high heat and toast (shake the pan frequently to prevent burning) the pecans or walnuts until they release their oil and are aromatic, approximately three minutes to five minutes. They should be slightly browned.
Remove the nuts from the pan and add the butter. When the butter is melted and lightly bubbling, add the mushrooms and saute for about five minutes, or until they release their water and begin to brown. Add the garlic and herbs, salt and pepper, and the nuts and stir to combine. Cook for another two minutes.
TO FILL THE MANICOTTI
Fill a pastry bag or a large plastic bag with a corner cut out with the pumpkin filling and squeeze it into the manicotti shells until full.
Evenly top with the mushroom mixture and cover with foil and bake for 15 minutes, or until the filling is hot in the center.