Place the cherry tomatoes on a baking tray and drizzle with 2 tablespoons of olive oil. Sprinkle on the oregano, salt and pepper then roll the cherry tomatoes around a few times to coat with the seasoned oil. Bake in the preheated oven until the tomatoes begin to burst, about 15 minutes.
Cook and drain the tortellini according to packet directions and set aside in a serving dish.
In a frypan, heat 2 teaspoons of olive oil over medium-low heat and cook and stir the garlic until golden brown, about 3 minutes. Remove the frypan from the heat and stir in the pesto and roasted tomatoes. Smash the tomatoes with a fork to break open, stir to combine and pour the sauce over the tortellini. Sprinkle with grated Parmesan cheese and torn basil leaves.