Peel, chunk, and rinse the sweet potatoes. Boil in a large pot for 15–20 minutes until fork-tender. Drain well.

Mash the drained sweet potatoes in a mixing bowl until smooth and creamy.

Mix in unsalted butter, milk, eggs, vanilla, cinnamon, nutmeg, and salt until fully blended.

In a separate bowl, combine flour, brown sugar, cinnamon, and salt. Cut in cold butter until it resembles coarse crumbs. Fold in chopped pecans.

Preheat the oven to 350°F (175°C). Grease a 9x13-inch baking dish. Pour the sweet potato mixture into the dish, then sprinkle the pecan streusel on top.

Bake for 30–40 minutes until the topping is golden brown and edges bubble slightly.

Remove from oven and let cool for about 10 minutes before serving.