Heat butter in a large nonstick pot over medium-high heat.
Add meatballs and cook them for a few minutes until they are golden brown.
Add the pasta sauce, diced tomatoes, beef broth (or water), Italian seasoning, salt and pepper and mix everything together.
Bring everything to a boil and add the uncooked pasta.
Reduce the heat to medium-low.
Cover the lid and let everything cook for 15-20 minutes.
Make sure to stir every 5 minutes to prevent the pasta from sticking to the pot.
Add a little more broth or water, if necessary.
Turn off the heat and stir in parmesan cheese and top it all off with mozzarella cheese.
Serve immediately and enjoy!
NOTES
Read all my tips above.
Leftovers can be stored in a sealed container in the fridge for up to 2 days and can be reheated in the microwave.