Slice the flat top off of each king oyster mushroom along with the very bottom 1/2cm of the stem (keep the mushroom offcuts for use in another recipe). Slice the stem into scallop shaped discs, keeping in mind that these will shrink slightly when cooked.
Place a large frying pan over medium heat and add 1 tbsp of the olive oil. Add the mushroom "scallops" and sear each side until nicely browned before flipping. Remove from the pan and set aside on a plate.
In the same frying pan over a medium heat, add the remaining 1 tbsp olive oil and bring to temperature. Add the shallot and fry for a minute or two, until turning translucent.
Add the minced garlic and fry for a further minute or two, stirring often. Follow with the capers and the white wine, being careful as the pan may spit when the wine is added. Stir well and reduce the heat to low and leave to simmer for 5-10 minutes.
Meanwhile, bring a medium saucepan of water to the boil and add a good few pinches of salt. Once boiling, add the pasta. Boil until al dente, stirring often.
Once the white wine sauce has reduced nicely, use a ladle to remove around 150-170ml boiling pasta water from the saucepan. Add it to the frying pan and bring to a simmer. Add the seared mushroom "scallops" along with the spinach, nutritional yeast, juice from the 1/2 lemon, dill, salt and pepper. Stir carefully and try not to break up the "scallops". Allow to simmer for a further 5-10 minutes or until the sauce is reduced and glossy.
If the sauce reduces too much, add another splash of pasta water. Once the pasta is cooked, drain and add it to the frying pan. Remove from the heat and stir everything together to coat.
Serve immediately with some more black pepper and a drizzle of extra virgin olive oil.