Preheat the oven to 375°F (190°C).
In a skillet over medium heat, cook the bacon until crisp. Remove with a slotted spoon and drain on paper towels.
In the same skillet, add the leeks and cook until softened. Remove from heat.
In a bowl, whisk together the eggs, heavy cream, and milk. Season with salt and black pepper.
Place the prepared pie crust in a pie dish. Spread the cooked bacon and leeks evenly over the crust.
Sprinkle the grated cheese over the bacon and leeks.
Pour the egg mixture over the fillings in the crust, spreading evenly.
Bake in the preheated oven for 35 to 40 minutes, or until the quiche is set and the top is golden brown.
Allow to cool slightly before serving. Enjoy your Easter Quiche with Bacon and Leeks!