Prepare the pie crust by rolling it out into a 13-inch circle and placing it in a 9-inch pie plate. Chill for 20 minutes.

Blind bake the crust at 425°F (220°C) for 10-12 minutes with weights, then bake for an additional 6-8 minutes until golden brown. Cool crust.

Whisk together eggs, heavy cream, milk, salt, and pepper until smooth and slightly frothy.

Add diced ham, shredded cheese, and green onions to the custard mixture, ensuring even distribution. Pour into pie crust.

Bake the quiche at 350°F (175°C) for 30 minutes, then add remaining ham and cheese. Bake for an additional 20-25 minutes until set.

Cool for at least 30 minutes before slicing to stabilize the filling. Garnish with green onions if desired.