Mushroom and leek/spinach Quiche

Name: Mushroom and leek/spinach Quiche
Prep time: 45 min
Cook time: 1 h
Total time: 1 h 45 min
Cuisine: European, Mediterranean, French
Ingredients: 3 eggs; 1 egg yolk; 1 cup spinach; 4 oz cremini mushrooms; 1/4 tsp cayenne; 1 cup Gruyère; 1 tbsp butter; 1 cup milk; 1/4 cup heavy cream; 1/4 cup onion; 2 tsp pepper; 1/2 tsp salt; 1/4 tsp nutmeg