Prep Time 15 minutes mins
Cook Time 10 minutes mins
Total Time 25 minutes mins
To make ahead, prepare the cream sauce (steps 1-4) the night before and store in the fridge. Reheat gently, then add spinach and eggs. Leftovers keep for up to 3 days; reheat in a low oven or stovetop with a splash of milk. For frozen spinach, thaw and squeeze dry before adding. Gruyère can replace cheddar, and nutmeg is non-negotiable. Season in layers for best flavor.