Boil salted water and cook pasta 2 minutes less than package directions for al dente. Reserve 1 1/2 cups pasta water before draining.
Heat olive oil in large skillet over medium heat. Add garlic and red pepper flakes, sauté 30 seconds until fragrant.
Add cherry tomatoes and cook 8-10 minutes, stirring occasionally, until blistered and burst. Press stubborn ones with spoon.
Stir in tomato paste and Italian seasoning. Cook 1-2 minutes, stirring constantly, until paste darkens.
Lower heat to medium-low. Add heavy cream and 3/4 cup reserved pasta water.
Stir in parmesan, ricotta, and salt. Simmer 5 minutes until thickened.
Add cooked pasta to skillet and toss to coat. Cook 2-3 minutes to finish cooking pasta in sauce.
Add more pasta water as needed to reach silky consistency.