Preheat the oven to 220 degrees Celsius / 428 Fahrenheit with top and bottom heat.
Take a large skillet, heat it over medium-high heat, and add a splash of olive oil. Sautée the onion and garlic briefly until they begin to turn translucent.
Meanwhile, cook the tortellini according to the package instructions.
Add the ground beef to the onion in the skillet and cook until crumbly, seasoning with oregano, paprika, salt, and pepper.
Pour in the passata and season the sauce further with salt and pepper if desired.
Add the cherry tomatoes to the sauce. Reduce the heat to low and let the sauce simmer for a few minutes.
Drain the cooked tortellini and toss with the sauce.
Spoon half of the pasta into the baking dish. Sprinkle half of the mini mozzarella balls over it, then add the other half of the pasta, and finally the rest of the mozzarella.
Spoon some green pesto over the top and place the baking dish in the oven for 10-15 minutes until the mozzarella has melted. Garnish with fresh basil to taste. Enjoy your meal!