Preheat your oven to 375°F (190°C). Prepare your pie dish by greasing if necessary.

Fit the pie crust into a 9-inch pie dish, pressing gently against the sides.

Heat oil over medium heat in a large skillet and add the ground beef. Cook until browned and crumbled, about 5-7 minutes.

Add the diced onion to the skillet and cook for about 3-5 minutes until softened.

In a separate bowl, whisk together the eggs and milk, then fold in the sautéed beef and onion mixture with half the shredded cheese.

Pour the beef filling into the prepared pie crust and top with the remaining shredded cheese.

Bake for 30-35 minutes until the filling is set and the crust is golden brown.

Let cool for a few minutes before serving, garnished with chopped parsley.