Preheat oven to 375° F (190° C). Grease a 9x13 oven-safe baking dish with a little butter.
Bake the sweet potatoes for 45-60 minutes, until they are easily pierced with a fork. Let them cool for 10 minutes before mashing.
6-8 medium sweet potatoes
Use a potato ricer or masher to mash the sweet potatoes into a large mixing bowl.
Combine the sweet potatoes, brown sugar, kosher salt, butter, spices, vanilla extract, and eggs with a hand mixer until the sweet potato mixture is creamy and well combined.
1 cup light brown sugar, ½ teaspoon kosher salt, 8 tablespoon unsalted butter, 2 teaspoon vanilla extract, 2 teaspoon ground cinnamon, ½ teaspoon ground nutmeg, 3 large eggs
Pour the sweet potato mixture into your prepared baking dish and smooth the top. Set it aside.
Mix the pecan topping ingredients together in a medium-sized bowl with a rubber spatula or with clean hands, it doesn't have to be perfectly well mixed, but just barely coming together. Sprinkle the mixture generously and evenly over sweet potatoes in the baking dish.
½ cup all-purpose flour, ½ cup brown sugar, 1 cup pecans, 1 teaspoon ground cinnamon, 4 tablespoons butter
Bake in the preheated oven for 50-55 minutes, the topping should be brown and crunchy. Let cool for at least 5 minutes before serving.