Hard Cooked Jesus Eggs

Eggs baked in the oven are destined for rubber - at least at my hands they are.
We celebrated Mother's Day with Andy's family at our house for brunch.  I had everything prepared ahead of time so it would be at little work as possible that morning.  That included this yuck egg dish.
2+ pounds of spinach cooked down into a tiny amount of cooked spinach, but well worth the time and effort to cook it up fresh with mushrooms, onions, and garlic.  I cooked this part the night before.  By time I was ready to bake, I made the wells with spoons and added each egg separately and carefully.
My propensity to overcook eggs in the oven starts with trying to cook too many dishes at one time.  The potato casserole and bacon were baking at the same time.  Thankfully Andy said the eggs worked better hard cooked.  I think he was being kind.  I think it depends on how you like your eggs.  I would imagine this dish would taste pretty yummy with a soft egg with a runny yolk.  Dip some toast and have a bit of spinach and mushroom - how can you go wrong?  Oh oh!! Call on me - I know!  Overcook your eggs. 
Baked Eggs with Spinach and Mushrooms
2 pounds (32 ounces) ounces fresh baby spinach or regular spinach leaves
1 small yellow onion, finely chopped
3 small garlic cloves, minced
4 tablespoons unsalted butter
1 pound mushrooms, thinly sliced
1 cup heavy cream
3/4 teaspoon table salt
Freshly ground black pepper
1/4 teaspoon freshly grated nutmeg (optional; I skip this)
12 large eggs
6 tablespoons finely grated Parmesan cheese
If you’ve just washed your spinach, no need to dry it before wilting it in the pan. If it’s already dry, bring 1/2 inch water to a boil in a very large ovenproof heavy skillet, then add half of spinach and cook, turning with tongs, until wilted, about 30 seconds. Add remaining spinach and wilt in same manner, then cook, covered, over moderately high heat until spinach is tender, about 1 to 2 minutes. Drain in a colander and cool under cold running water. Gently squeeze handfuls of spinach to remove as much liquid as possible, then coarsely chop. You will have about 2 cups fairly tightly packed cooked spinach.
Wipe skillet dry, then melt butter over medium-low heat. Cook onion and garlic until softened, 2 to 3 minutes. Add mushrooms and increase heat to medium-high, then cook, stirring, until mushrooms have softened, exuded liquid and that liquid has cooked off, about 5 minutes. Stir in cream, salt, pepper, nutmeg (if using), and chopped spinach and bring back a simmer. Remove skillet from heat.
If baking eggs in this skillet, make 12 large indentations in mixture, each large enough to fit an egg. Otherwise, you can transfer this mixture to a 9×13-inch baking dish and do the same there.
Do ahead: You can then set this aside for a few hours or up to one day in the fridge, covered.
When you’re ready to bake the dish, or about 30 minutes before serving, put oven rack in upper third of oven and heat oven to 450°F. Crack an egg into each well. Bake until whites are firm and yolks are still runny. You can check this by inserting a toothpick into various parts of the eggs and seeing whether they’re runny or set, which takes anywhere from 15 to 30 minutes. The range is long due to different ovens and baking vessels. It’s better to have to check more often than to let them overcook.