Make the mashed potatoes according to recipe instructions.
Layer half of the mashed potatoes in a casserole dish.
Top with the cheese and add the rest of the mashed potatoes. In a small bowl, combine the breadcrumbs, garlic, salt, pepper and olive oil.
Top the mashed potatoes with the breadcrumbs.
Place the mashed potato casserole in a preheated oven and bake for 15-20 minutes or until the top is golden brown and the casserole is hot and bubbling.
Remove from the oven, allow to cool for 5 minutes then serve scattered with chopped parsley.