Heat some butter in the pan. Halve the bread roll, toast briefly in it.
Heat the butter and oil together in the pan. Lightly fry the onion and garlic in it. Spread the spinach on top and let it collapse, covered. Season with salt and pepper.
Spread half a bread roll with a little hollandaise sauce and add plenty of spinach. Place the poached egg on top and pour the hollandaise sauce over it, then garnish with dill.