In a blender or blender cup add 1 cup cashews and ½ cup water. You may allow this to soak for up to an hour, but it will still be creamy if not soaked.
Bring a large pot of water to a rolling boil and add the pasta. Boil for 6-8 minutes until al-dente. Reserve some pasta water to add to the sauce.
In a pan, add a few tbsps of extra virgin olive oil and saute shallots and garlic until softened. Season with salt, pepper and rosemary or Italian seasoning.
Add shallots and garlic to the blender cup, along with roasted red pepper, chopped.
Blend until smooth. Add starchy pasta water as necessary. Adjust salt and seasoning to taste.
In the same pan you cooked the onions and garlic, add a few more tbsps of olive oil and saute the mushrooms until browned and all the water is released. Set aside and saute the asparagus until crisp and tender, for 3-4 minutes.
Combine the sauce with the pasta, adding more pasta water as necessary to thin out the sauce. Top with veggies and a sprinkle of crushed red pepper flakes.