Preheat your oven to 375°F (190°C). Halve 1 cup of cherry tomatoes and shred mozzarella if not pre-shredded.
Bring a large pot of salted water to a boil. Cook 2 cups of cheese tortellini according to package instructions (3-5 minutes). Drain and transfer to a large mixing bowl.
Add 1 cup of pesto sauce, halved cherry tomatoes, and 1 tablespoon olive oil to the warm tortellini. Toss gently to coat. Season with salt and pepper to taste.
Transfer the mixture to a prepared baking dish. Sprinkle 1 cup shredded mozzarella evenly over the top, then 1/2 cup grated Parmesan cheese.
Bake in the preheated oven for 15-20 minutes until cheese is melted, bubbly, and starting to brown. Tomatoes will soften and release juices.
Remove from oven carefully using oven mitts. Let rest a few minutes. Garnish with fresh basil leaves and serve warm.
