Classic French Spinach Quiche - Once Upon a Chef

Ingredients

• 1 9-inch deep dish frozen pie crust
• 1 tablespoon butter
• ½ cup thinly sliced shallots
• 4 large eggs
• 1¼ cups heavy cream
• Pinch ground nutmeg
• ¾ teaspoon salt
• ⅛ teaspoon cayenne pepper
• 1 cup (4 oz) finely shredded Gruyère, packed
• 1 10-ounce package frozen chopped spinach, defrosted and wrung free of water