Preheat your oven to 375°F (190°C).

In a large, oven-safe skillet, heat a drizzle of oil over medium-high heat. Add the lean ground beef and diced yellow onion, sautéing them together until the meat is browned and the onions are softened, about 3-4 minutes.

Drain any excess fat from the skillet. Add minced garlic, Italian seasoning, kosher salt, and freshly cracked black pepper; continue sautéing for another 1-2 minutes.

Stir in the marinara sauce along with the uncooked refrigerated tortellini. Fold everything together evenly. Sprinkle in a little more than half of the shredded mozzarella, mixing well before spreading the mixture evenly across the skillet. Top it with the remaining cheese.

Cover your skillet tightly with aluminum foil and place it in the preheated oven for 30 minutes.

After 30 minutes, remove the foil and check if the tortellini is tender. If it is, set your oven to broil and allow the Baked Tortellini to broil for 1-3 minutes until the cheese is bubbly and lightly golden.

Once done, remove the skillet from the oven and let it rest for a few minutes. Garnish with fresh parsley or basil before serving.