3 tablespoons unsalted butter, plus more to butter ramekins
2 tablespoons minced yellow onion
Salt and freshly ground black pepper
6 ounces baby spinach
4 slices Canadian bacon
4 large eggs
1/4 cup heavy cream
1 ounce grated aged Cheddar, plus extra for serving
Sourdough bread

Heat oven to 350 degrees F and arrange rack in middle.
Butter 4 (6-ounce) ramekins and set aside.
Melt 1 tablespoon butter in a large frying pan over medium heat.
When it foams, add onion, season well with salt and freshly ground black pepper, and cook until softened, about 1 minute.
Add spinach and cook until spinach is well wilted, about 2 minutes.
Place ham on bottom of ramekins and top with spinach.
Crack eggs into ramekins, place 1 tablespoon cream over each egg, and divide half of cheese evenly among ramekins.
Put ramekins on a baking sheet and bake, rotating pan halfway through baking, until whites are just set but yolks are still runny, about 15 to 18 minutes.
Meanwhile, spread remaining 2 tablespoons butter on 4 slices sourdough bread.
Top with grated cheese and toast until bubbly.