Cook the pasta.
Bring the water and salt to a boil in a large pot. Add the pasta and cook until al dente according to the package directions.
Before draining, reserve 1 cup of pasta cooking water. Drain the pasta without rinsing.
Cook the garlic.
Heat the olive oil in a large, deep skillet over medium-low heat. Add the crushed garlic and cook for 30–60 seconds, stirring until fragrant. Avoid letting it brown.
Make the sauce.
Add the Boursin cheese and about 1/2 cup of the reserved pasta water. Stir gently until the cheese melts into a smooth sauce.
Reduce the heat to low and gradually stir in the Parmesan. Add half the chopped basil and cook gently for about 2 minutes.
Toss in the pasta.
Add the cooked pasta and toss until evenly coated. Gradually add more reserved pasta water as needed to create a creamy sauce that clings to the pasta.
Add the tomatoes.
Gently stir in the halved cherry tomatoes. Cook over medium-low heat for another 2 minutes, just until warmed through.
Finish and serve.
Top with the remaining fresh basil and serve immediately.