spinach quiche recipe

Ingredients**: - **For the Crust**: - 1 1/4 cups all-purpose flour - 1/2 tsp salt - 1/2 cup cold unsalted butter, cubed - 4-5 tbsp ice water - **For the Filling**: - 1 tbsp olive oil - 1 small onion, finely chopped - 3 cloves garlic, minced - 6 cups fresh spinach, chopped - 4 large eggs - 1 cup heavy cream - 1/2 cup milk - 1 cup grated Gruyère or Swiss cheese - 1/4 cup grated Parmesan cheese - Salt and pepper to taste - Nutmeg, a pinch (optional)