Preheat oven to 375 degrees and put a pot of water on to boil.
Put tomatoes on a cooking sheet and sprinkle with 1 tbsp. olive oil, salt and pepper and then place in the preheated oven. Roast for 10 minutes, or until they begin to burst.
Meanwhile, once water boils, add pasta to the water and cook until al dente.
In a separate skillet, melt 2 tbsp. butter and once melted, add the olive oil. Add onions and saute 2-3 minutes or until they begin to soften. Add garlic cloves. Once tomatoes are done, add to the pan and make sure to scrape all the tomato juice from the cooking sheet. Cook over very low heat as to not cook the tomatoes down to mush.
Once pasta is done, add tomato and oil mixture to pasta and toss to coat. Add fresh mozzarella pearls and stir quickly to incorporate. If you like the taste of extra virgin olive oil, add the tablespoon now. Taste and season for salt and pepper. Add quickly to serving bowls so you don't melt the mozzarella.
Garnish with parmesan cheese and basil. Enjoy!
Notes
Store leftovers in the fridge in an airtight container for up to 7 days.