Cook the pasta according to the instructions and then let it cool down. Cut the onions into small cubes and fry them in a pan with the bacon. Quarter the cherry tomatoes and chop the spinach leaves as desired. Put the pasta, onions, bacon, tomatoes and spinach in a bowl.
For the dressing, puree the anchovies, yoghurt, oil, lemon juice and Worcestershire sauce with a hand blender until the anchovies are crushed. Add the parmesan and season with garlic powder, parsley, pepper and, if necessary, a little salt.
Pour the dressing over the pasta and mix well. Sprinkle with the coarsely grated Parmesan cheese to serve.