Preheat the over to 375ºF . Bring a full kettle of water to a boil.
Place a large pan over medium heat with the butter. When the foam subsides, add the spinach and cook until wilted, about 8 minutes. Transfer to colander. When cool enough to handle, gently press the spinach to remove the excess moisture.
Generously coat 8 (6-ounce) ceramic ramekins with non-stick cooking spray. Divide the cooked spinach between the ramekins, followed by the crushed tomatoes. Crack 1 egg into each ramekin, followed by 1 tablespoon heavy cream and 1/2 tablespoon cheese. Season with salt and pepper to taste.
Place a (9-by-13) baking dish on the rack of the oven. Place the ramekins in the baking dish, then pour the boiling water into the baking dish so it comes halfway up the sides of the ramekins.
Bake until the egg whites are set and the yolks are still runny, about 12 minutes.
Use tongs to remove the ramekins from the water bath and land on a dish towel.
Garnish with a pinch of basil and serve hot.