Preheat your oven to 425°F (220°C).
Wash and scrub the potatoes thoroughly. Pat them dry with a kitchen towel.
Place a potato on a wooden spoon to ensure you don’t cut all the way through. Grab your sharp knife and slice away about 1/8-inch apart across your potatoes.
In a small bowl, combine the melted butter, olive oil, minced garlic, salt, pepper and cayenne pepper. Stir well to mix.
Brush each potato generously with the butter mixture, ensuring it gets into the slices.
Transfer the potatoes to a roasting tray. Bake them in that preheated oven for 30 minutes. Take out the potatoes from the oven after 30 minutes and brush them with remaining butter mixture.
Place the potatoes back in the oven and bake for a further 30 minutes or until crisp and golden.
Once they’re ready, take ‘em out. Garnish with freshly chopped parsley.
Serve Hasselback Potato Roast with grilled salmon or stuffed portobello mushrooms.