Preheat your oven to 375°F (190°C). Gather your ingredients and set taco shells in a greased baking dish.

In a large skillet, heat olive oil over medium heat. Add diced onion and minced garlic; sauté until the onion is translucent, about 2-3 minutes.

Add ground beef to the skillet, breaking it up as it cooks. Stir occasionally until browned, about 5-7 minutes. Stir in taco seasoning and tomato sauce, simmer for 5 minutes.

Spoon the meat mixture into the taco shells, then sprinkle shredded cheese on top.

Bake in the preheated oven for 10-15 minutes until cheese is melted and shells are golden brown.

Remove from oven, let cool for a couple of minutes, then top with fresh toppings as desired.