Preheat oven to 220°C / 430°F.
Cook the pasta for 1-2 minutes less than what's stated on the package instructions. Save ⅓ cup pasta water.
Roast the cherry tomatoes. Cut them in half and add them to a pan that fits them. Drizzle with 2 tablespoons of olive oil and season with salt. Roast for 10-15 minutes.
Save half of the cherry tomatoes in a bowl to add to the sauce later on. Allow the tomatoes to cool slightly.
Blend the remaining half of the cherry tomatoes, along with the pan juices, and thyme. Use either a high-speed blender or food processor and pulse until you get a smooth sauce.
Heat the remaining olive oil (3 tablespoons) in a non-stick frying pan.
Saute the onion over medium-low heat until soft then add the garlic and cook for 2 minutes more.
Pour in the sauce and pasta water. Taste and season with salt if needed.
Add the basil leaves, and dried oregano, and cook for a minute.
Stir in the pasta and then the cherry tomatoes.
Serve with freshly ground pepper on top.