In a large skillet, heat the olive oil and cook the diced white onion for about 3 minutes until lightly translucent.
Add gently the 'nduja and gently break it down. If necessary add some warm water so that it helps the 'nduja to break down and emulsify even further.
Once that the 'nduja has fully dissolved, add the tomato passata and mix well. Let the mixture cook for about 15 minutes on low heat.
In the meantime, bring to boil a pot filled with water. Once it starts to boil, season with plenty of salt. Add the pasta and cook as instructed on the package or until al dente.
As soon as the pasta is ready, add it to the sauce and mix well until all the pasta is covered with the sauce. Add salt and pepper as required.
Serve immediately and top it with the fresh burrata cheese.