Preheat the oven to 200C (180C fan forced).
Place the cherry tomatoes in a large baking tray. Drizzle over the olive oil, scatter over the sliced garlic and the oregano, and season well with salt and pepper.
Toss everything together, ensuring the tomatoes are well coated in the olive oil.
Pat the tomatoes into a single layer across the bottom of the baking tray, and put the tray in the oven.
Bake the tomatoes for 20 - 25 minutes, or until the tomatoes have started to burst and the juices are seeping out. Don't allow the tomatoes to blacken too much.
Remove the tray from the oven, and scatter the chopped basil over the tomatoes.
Stir gently to incorporate the basil, and to slightly break up the tomatoes.
The sauce can be cooled and frozen at this stage.