Preheat oven to 400°F (200°C).

Toss garlic cloves with a drizzle of olive oil and a pinch of salt.

Wrap tightly in aluminum foil and roast for 30 minutes, or until soft. For a deeper flavor, roast longer, checking every 10 minutes until golden brown.

Peel potatoes and place them in a bowl of cold water to prevent browning.

Cut into 1-inch cubes and place in a large pot.

Add 2 teaspoons salt and enough cold water to cover the potatoes.

Bring to a gentle boil over high heat, then reduce to low and simmer for 12 minutes, or until fork-tender.

Drain potatoes and transfer to a large mixing bowl.

Squeeze roasted garlic from skins and add to the potatoes.

Mash with a potato masher, ricer, or press through a fine mesh sieve for extra smoothness.

In a small saucepan, combine heavy cream and rosemary sprigs.

Simmer over low heat for a few minutes, then remove from heat.

Strain to remove rosemary.

Stir melted butter into the potatoes until well combined.

Gradually add the rosemary-infused cream, stirring until smooth and creamy.

Season with additional salt and freshly ground black pepper to taste.

Serve warm, topped with an extra pat of butter if desired.