Prepare the quiche crust, if making from scratch. Or follow instructions of the package if using store bought. Reserve.

Preheat oven to 350F degrees.

In a large skillet, heat the olive oil - over medium high heat - and brown the sausage, breaking it into crumbles with a wooden spoon, about 5 minutes. When the sausage is no longer pink but not yet completely browned, add the onion and continue cooking until sausage is browned and onions are tender, about 3 minutes. Reserve.

In a large bowl, whisk together the eggs, half and half, cheese, parsley, salt and pepper.

Spoon sausage mixture into the pie crust and pour the custard on top of that, arranging with a fork if necessary.

Bake the quiche in the preheated oven for 30 to 40 minutes or until set and golden brown.

Let it cool slightly before serving. You can also make it overnight and serve it at room temperature.