Bring a large pot of salted water to boil and cook pasta according to package directions until al dente. Drain and set aside.
While pasta cooks, heat 1 tablespoon olive oil in a large skillet over medium-high heat.
Season diced chicken with salt and pepper, then cook in the skillet until golden brown and cooked through, about 6-7 minutes. Remove chicken and set aside.
In the same skillet, add remaining tablespoon of olive oil. Add diced onion and cook for 2-3 minutes until softened.
Add minced garlic and cook for 30 seconds until fragrant.
Add cherry tomatoes and cook until they begin to burst, about 3-4 minutes.
Reduce heat to medium-low and add heavy cream, stirring to combine. Bring to a gentle simmer.
Add cooked chicken back to the skillet, then stir in Parmesan cheese until melted.
Add Italian herbs and red pepper flakes (if using). Season with salt and pepper to taste.
Add the cooked pasta to the skillet and toss until well coated in the sauce.
Garnish with fresh basil leaves and additional Parmesan cheese if desired.
