Preheat the oven to 180°C /160°C fan/Gas 4. Place 2 ramekin dishes on a baking tray and warm in the oven for 5 minutes.
Use half the butter to grease the ramekins. Season the spinach and mix with the pesto, then divide between the bases of each dish, making a slight well in the centre.
Carefully break two eggs into each dish. Season and dot with the remaining butter. Place the dishes in a small roasting tin and fill with enough boiling water to come halfway up the sides of the dishes. Bake for 8-9 minutes until the edges of the egg whites are just beginning to set.
Drizzle over the cream and sprinkle on half of the Parmesan cheese. Return to the oven for 5-6 minutes until the egg whites are set and the yolks are set but still runny. Sprinkle with remaining cheese. Try serving with the buttered toast, cut into soldiers, or crusty bread.