Shortcut Spanakopita

Name: Shortcut Spanakopita
Ingredients: 1 1⁄2 teaspoons extra virgin olive oil; 1 small onion, finely chopped; 10 ounces frozen chopped spinach, defrosted and squeezed dry; kosher salt & freshly ground black pepper, to taste; 1⁄4 teaspoon nutmeg (ground or freshly grated); 4 -6 ounces feta cheese, crumbled; 1 egg, beaten; 3 tablespoons sour cream; 4 sheets phyllo dough (13 x 17 inches each); 3 tablespoons butter, melted