Step 1: Roast the Garlic

1. Preheat your oven to 400°F (200°C).
2. Slice off the top of the garlic head to expose the cloves. Drizzle with olive oil and wrap it in aluminum foil.
3. Roast in the oven for 30-35 minutes until the garlic is soft and golden brown.
4. Once cooled, squeeze the garlic cloves out of their skins and mash them into a paste.

Step 2: Boil the Potatoes

1. Place the cubed potatoes in a large pot of salted water.
2. Bring to a boil over medium-high heat and cook for about 15-20 minutes or until the potatoes are fork-tender.
3. Drain the potatoes well and return them to the pot.

Step 3: Prepare the Mashed Potatoes

1. Add the roasted garlic paste, butter, milk, and sour cream to the potatoes.
2. Mash the potatoes using a potato masher or electric mixer until smooth and creamy.
3. Stir in the grated Parmesan cheese.
4. Season with salt and pepper to taste. Mix well to ensure the flavors are evenly distributed.

Step 4: Make the Parmesan Crumble

1. In a small bowl, combine panko breadcrumbs, grated Parmesan cheese, melted butter, dried parsley, garlic powder, salt, and pepper.
2. Mix well until the breadcrumbs are evenly coated with the butter and seasoning.

Step 5: Assemble and Bake

1. Preheat your oven to 375°F (190°C).
2. Transfer the mashed potatoes to a baking dish and spread them out evenly.
3. Sprinkle the Parmesan crumble mixture evenly over the top.
4. Bake for 15-20 minutes or until the topping is golden brown and crispy.