Instructions

1. Cut 8 tablespoons of the unsalted butter into 1/2-inch cubes. Place 2 large eggs in a small bowl and lightly beat with a fork to break up. Place 1 cup half-and-half or whole milk on the counter. Let everything sit at room temperature until the butter is softened. Meanwhile, boil the potatoes.
2. Peel 3 pounds sweet potatoes, cut into 2-inch chunks, and place in a large saucepan. Add 1 tablespoon of the kosher salt and add enough cool water to cover by about 1 inch. Bring to a boil over medium-high heat. Reduce the heat to maintain a simmer and cook until the potatoes are very tender, about 20 minutes. Meanwhile, heat the oven and prepare the topping.
3. Arrange a rack in the middle of the oven and heat the oven to 350ºF. Coat a 9x13-inch baking dish with butter.
4. Place the remaining 4 tablespoons unsalted butter in a medium microwave-safe bowl and microwave on HIGH until melted, 40 to 50 seconds. Coarsely chop 1 1/4 cups pecans. Add the pecans, 1/2 cup of the packed brown sugar, 1/3 cup all-purpose flour, 1/2 teaspoon ground cinnamon, and 1/4 teaspoon of the kosher salt to the butter. Stir to combine.
5. When the potatoes are ready, drain and return to the pot. Let cool for 5 minutes.
6. Use a potato masher to mash the sweet potatoes in the pot until mostly smooth. Add the reserved butter, eggs, milk or half-and-half, remaining 3/4 cup packed brown sugar, 1 teaspoon vanilla extract, and remaining 3/4 teaspoon kosher salt. Stir to combine. Transfer the mixture to the baking dish and spread into an even layer. Sprinkle the topping in an even layer over the potatoes.
7. Bake until set and the top is lightly browned, 30 to 40 minutes. Let cool for 5 minutes before serving.