- For the Sweet Potato Filling: 
- Peel and chop sweet potatoes. Boil or steam until fork-tender, about 15–20 minutes. Drain and mash until smooth. 
- In a large bowl, combine mashed sweet potatoes, sugar, melted butter, eggs, vanilla, milk, cinnamon, and a pinch of salt. Mix until smooth. 
- Pour the sweet potato mixture into a greased 9x13-inch baking dish and spread evenly. 
- For the Streusel Topping: 
- In a medium bowl, mix brown sugar and flour. 
- Stir in melted butter until crumbly. 
- Fold in chopped pecans. 
- To Assemble and Bake: 
- Sprinkle streusel topping evenly over the sweet potato filling. 
- Bake at 350°F (175°C) for 30–35 minutes until the topping is golden brown. 
- Let rest for 10 minutes before serving for best texture.