In a large saucepot add cashews (if you didn’t soak them), cauliflower, garlic, a pinch of salt, bay leaf and 3 cups of water. Cover and bring to a slow boil over a medium-high heat.
Cook for 10-15 minutes or until the cauliflower easily breaks apart. Strain and remove the bay leaf.
Transfer mixture to a high-speed blender (add cashews at this point if you pre-soaked them). Add pine nuts, miso and salt. Begin blending on low-speed while slowly adding the soy milk. Once incorporated, blend on high for couple minutes until the mixture is silky smooth.
Set aside half of the mixture for this recipe and save the remaining mixture in a closed container in the fridge for up to a week for other use.
To make the mushrooms
Preheat oven to 190C/375ºF/gas mark 5.
Add sliced shiitakes to a small bowl and toss with 1 tease spoon of the oil, smoked paprika and pinch of black pepper. In a large oven-safe skillet, heat 2 tablespoons of oil on the stovetop over medium-high heat. Add shiitake mushrooms and sauté for 2 minutes, then transfer pan directly to oven and finish roasting for 10 minutes. Remove and transfer the mushrooms to a paper towel to allow to drain and crisp up.
To complete the dish
Cook fettuccine al dente according to the package instructions, set aside.
Heat large saucepot on medium heat until hot, then add oil, onions and sliced garlic cloves and sauté for 3 minutes until they begin to brown. Add a splash of water (or white wine if handy) to loosen, then half of the alfredo-style sauce, peas and mushrooms.
Heat for 1 minute then add pasta and stir to coat.
Remove from heat and garnish with the parsley, black pepper and salt, to taste.