Spinach, Green Onion, and Smoked Gouda Quiche

Crust: place butter in a large bowl and beat with a mixer until light and fluffy. Combine milk, salt and egg yolk in a small bowl and stir will with a whisk. Add milk mixture to butter, 1 Tablespoon at a time, beating well after each addition. Add flour, beat just until combined. Press mixture into a 4 inch circle on plastic wrap and cover. Chill for 1 hour. Preheat oven to 350 degrees. Unwrap and place chilled dough on lightly floured surface. Roll into 10 inch circle. Fit dough into a 9 inch pie plate that has been prepared with non-stick cooking spray. Freeze 15 min. Bake at 350 degrees for 25 min or until lightly browned. Cool. Filling: heat oil in large skillet and add onions, saute 5 min or until tender. Add spinach and saute for 2 min until wilted. Combine 1 cup milk and remaining ingredients in a bowl and stir well with a whisk. Stir in spinach mixture. Pour filling into crust. Bake at 350 degrees for 35 min. Cool and cut into wedges.