Trim the flat top and bottom ½ cm of each king oyster mushroom and save the offcuts for another dish.
Slice the stems into round scallop-like pieces, remembering they will shrink when cooked.
Heat 1 tablespoon of olive oil in a large frying pan over medium heat, then add the mushroom slices.
Sear on each side until golden brown, then transfer them to a plate.
Using the same pan, add the remaining 1 tablespoon of olive oil and heat over medium.
Sauté the shallot until translucent, then stir in the minced garlic and cook for another couple of minutes.
Add capers and pour in the white wine carefully, as the pan may sizzle.
Stir well, reduce the heat to low, and let it simmer for 5-10 minutes.
Meanwhile, bring a medium saucepan of salted water to a boil.
Add the pasta and cook until al dente, stirring occasionally.
Once the wine sauce has reduced, ladle about 150-170ml of boiling pasta water into the pan.
Bring it to a simmer, then add the seared mushroom "scallops," spinach, nutritional yeast, lemon juice, dill, salt, and pepper.
Stir gently, being careful not to break the mushrooms, and let it simmer for another 5-10 minutes until the sauce thickens and turns glossy.
If the sauce thickens too much, add a little more pasta water.
Drain the pasta and mix it into the pan, stirring to coat everything evenly.
Remove from heat and serve immediately with extra black pepper and a drizzle of olive oil.