1/2 stick (4 tablespoons) unsalted butter, melted, plus more for buttering the baking dish 3 to 4 large sweet potatoes (about 1 3/4 pounds), peeled and cubed 1/2 cup milk
1/4 cup brown sugar, packed 1 teaspoon pure vanilla extract 1/2 teaspoon kosher salt 2 large eggs
1/2 cup all-purpose flour 1/2 cup brown sugar, packed 1/2 stick (4 tablespoons) unsalted butter, melted 1/4 teaspoon kosher salt 3/4 cup chopped pecans
In a large saucepan of salted water, combine 1 3/4 pounds peeled and diced sweet potatoes.
Bring to a boil over high heat, then reduce to a simmer and cook for 15 to 20 minutes, or until the potatoes are very soft. Drain and allow to cool. Sweet potatoes should be mashed.
To make the filling: Preheat the oven to 350 degrees Fahrenheit. Grease a 2-quart baking dish.
In a large mixing basin, combine the butter, mashed sweet potatoes, milk, brown sugar, vanilla, salt, and eggs. Place in the prepared baking dish.
In a medium mixing basin, combine the flour, brown sugar, butter, and salt until wet and the dough clumps together. Add the pecans and mix well. Spread the mixture evenly over the top of the sweet potatoes.
Bake for 25 to 30 minutes, or until the center is mostly set and the top is brown. Serve immediately.