Place the cubed potatoes in a large pot and cover with cold water. Add a pinch of salt and bring to a boil over medium-high heat. Cook until the potatoes are tender, about 15-20 minutes. Drain and return to the pot.

In a small saucepan, melt the butter over medium heat. Continue cooking, stirring frequently, until the butter turns golden brown and has a nutty aroma, about 5-7 minutes. Add the minced garlic and cook for an additional 1-2 minutes until fragrant.

Pour the brown butter and garlic mixture over the drained potatoes. Add the whole milk, sour cream, salt, and black pepper.

Mash the potatoes using a potato masher or a hand mixer until smooth and creamy. Adjust seasoning to taste.

Transfer the mashed potatoes to a serving bowl and garnish with chopped parsley, if desired. Serve warm.