- 7 tbsp Unsalted Butter, divided
- 1 1/2 cups Onion , thinly sliced
- 1 large Leek (white and light green part only), halved lengthwise and vertically sliced
- 1 tsp Sugar
- 2 pounds Russet potatoes, peeled adn cut into 1-inch pieces
- 2/3 cup Half and half
- 1/2 tsp Salt
- 1/4 tsp White pepper
- Melt 2 tbsp of the butter in a 10-inch nonstick skillet over medium heat. Add the onion, leek, and sugar; cook, stirring occasionally, until golden, about 14-15 minutes. Remove from the heat.
- Meanwhile, combine the potatoes in a large saucepan with enough cold water to cover by 2 inches. Bring to a boil over medium-high heat. Reduce heat to medium and simmer until potatoes are tender, about 14-15 minutes. Drain; return potatoes to the saucepan.
- While the potatoes cook, combine the remaining 5 tbsp butter and half and half in a small saucepan over medium-high heat. Cook until the butter is melted. Pour into the potatoes and mash. Stir in onion mixture, salt, and pepper.