Preheat the oven to 400 degrees . In a large, ovenproof skillet, crisp the bacon over medium heat, 8 to 10 minutes. Transfer to a paper-towel-lined plate. Pour off all but 1 tbsp. of fat.
Add the onion and cook, stirring occasionally, until slightly softened, about 3 minutes. Stir in half of the spinach and cook, turning with tongs, until wilted, about 2 minutes. Repeat with the remaining spinach. Carefully pour off some of the liquid; season the spinach with salt and pepper. Add the cream and simmer until slightly thickened, 2 minutes.
With a spoon, make 8 small wells in the spinach. Crack an egg into each hole. (The eggs will spread and run together a bit.) Sprinkle with the cheese. Transfer to the oven and bake until the egg whites are set but the yolks are slightly runny, 6 to 8 minutes. Spoon into shallow bowls; serve with the bacon.