Preheat oven to 350°F. Grease 4 remekins or individual shallow baking dishes; set aside.
Heat oil in a medium saucepan. Add onions and cook until tender. Add mushrooms and cook for 5 minutes. Stir in spinach, 1 teaspoon salt, pepper and peaches. Divide mixture equally among prepared ramekins, making a depression in the center of each. Bake for 15 to 20 minutes or until mixture is hot (depending upon depth in dish). Add 1 egg to the depression in each dish. If desired, sprinkle with additional sea salt and pepper. Bake 7 to 10 minutes more or until egg white is set.