Linguine with miso butter, shitake and spinach

Name: Linguine with miso butter, shitake and spinach
Prep time: 10 min
Cook time: 20 min
Total time: 30 min
Cuisine: Asian, Japanese
Ingredients: 190g dried linguine (or spaghetti); 1 tbsp olive oil; 100g unsalted butter, fridge-cold, cut into 2cm cubes; 1 banana shallot, finely chopped (75g); 150g fresh shiitake mushrooms, roughly sliced; 3 garlic cloves, crushed; 50g white miso paste; 1 tsp light soy sauce; 1 tbsp Chinkiang black (or malt) vinegar; 150g baby spinach leaves salt and black pepper; shichimi togarashi (or chilli flakes); lemon or lime wedges