1/2 pound (225g) dried spaghetti
Kosher salt
1/2 cup (120ml) extra-virgin olive oil, divided
4 medium cloves garlic, thinly sliced or finely chopped by hand (see note above)
4 to 6 anchovy fillets, finely chopped (1 1/2 to 2 tablespoons; 20–30ml chopped anchovy)
Large pinch red pepper flakes
1/4 cup capers, drained and chopped (about 2 ounces; 60g) (see note above)
1/4 cup chopped pitted black olives (about 2 ounces; 60g) (see note above)
1 (14-ounce; about 400g) can whole peeled tomatoes, preferably San Marzano, roughly broken up by hand
Small handful minced fresh parsley leaves
1 ounce (30g) finely grated Pecorino Romano or Parmesan cheese, plus more for serving
Freshly ground black pepper
1 (5-ounce; 140g) can oil-packed tuna (optional)