Preheat the grill to a medium setting.
Melt 75g of butter in a small saucepan over low heat.
Beat egg yolks in a bowl over simmering water until pale and thick.
Add water, lemon juice, and seasoning to the yolks and beat for 30 seconds.
Stir in half of the remaining solid butter until the mixture thickens.
Remove from heat and beat in the final piece of solid butter.
Whisk in the 75g melted butter slowly until the sauce reaches cream consistency.
Place buttered muffins on a baking tray.
Layer steamed spinach, poached eggs, and hollandaise sauce onto the muffins.
Grill for 1 to 2 minutes until bubbling and golden.
Serve the eggs Florentine immediately on plates.