For the carrot and spinach casserole, preheat the oven to 180 degrees and grease a loaf pan. Wash the spinach and remove hard stems.
Place the spinach wet in a saucepan, salt and steam over very low heat for about 5 minutes until soft, stirring constantly. Then drain, squeeze, chop finely and season with salt and nutmeg.
Mix the grated carrots with the orange zest and season with salt and pepper. Place half of the carrots in the bottom of the loaf pan, cover with the spinach and spread the second half of carrots on top of the spinach.
Melt the butter in a saucepan and pour over the carrots. Then bake the carrot and spinach casserole in the oven for about 1 hour.