Preheat your oven to 375°F. Place the pie crust into a pie dish. Press gently and shape the edges. Prick the bottom with a fork. Bake for 10 minutes until lightly golden.

Heat a frying pan over medium heat. Add chopped bacon and cook until crispy. Stir often to cook evenly. Remove the bacon and place it on paper towels to drain extra fat.

In the same pan, add chopped onions. Cook in the bacon fat for extra flavor. Stir until soft and slightly golden. This step adds sweetness and depth to the filling.

In a large bowl, whisk the eggs until smooth. Add heavy cream and milk. Mix well. Add salt, pepper, and a pinch of nutmeg. Stir gently to combine everything evenly.

Spread the cooked bacon and onions over the pre-baked crust. Sprinkle shredded Gruyère cheese on top. Pour the egg mixture slowly over the filling so it spreads evenly.

Place the pie dish in the oven. Bake for about 35 to 40 minutes. The center should be set but slightly soft. The top will turn golden and smell amazing.

Remove the quiche from the oven and let it cool for 10 minutes. Slice carefully and serve warm. The texture will be creamy and smooth with a crisp crust.