Step 1

Heat the oven to 450 degrees F and arrange a rack in the middle.

Step 2

In a larger bowl, toss the tomatoes with kosher salt, black pepper, garlic and extra virgin olive oil. Transfer to a sheet-pan and bake in heated oven 25 to 35 minutes or just until the tomatoes collapse and develop some char (if you don't want them too soft, take the tomatoes out earlier). When ready, remove from the oven. (See notes)

Step 3

While the tomatoes are roasting, cook the spaghetti in boiling water according to the package to al dente (about 10 minutes). Reserve ½ cup of the pasta cooking water. Drain the pasta.

Step 4

Transfer the cooked spaghetti to a large bowl (same bowl used earlier for the tomatoes). Add the pesto and toss to coat. If you need to, add a little bit of the pasta cooking water to help mix it evenly. Taste, and if needed, add a bit of kosher salt and black pepper to season.

Step 5

Add the roasted tomatoes and mozzarella to the bowl of pasta. Toss to combine. Serve warm. Garnish with fresh basil, if you like.