Peel and cube your sweet potatoes first.
Boil them in salted water for 20 minutes.
They should be fork-tender when done.
Drain the water completely and mash them smooth.
Combine mashed sweet potatoes with sugar in a bowl.
Add beaten eggs, melted butter, and milk.
Stir in vanilla extract until everything blends.
Mix until the texture is creamy and smooth.
Preheat your oven to 350°F (175°C).
Grease your 9x13 inch baking dish lightly.
Pour the sweet potato mixture into the dish.
Spread it evenly across the bottom.
Mix brown sugar and flour in another bowl.
Add melted butter and stir it well.
Fold in chopped pecans until everything combines.
This creates a streusel-like topping.
Sprinkle the pecan mixture over the casserole.
Spread it evenly across the top layer.
Bake for 30-35 minutes until golden brown.
The edges should bubble slightly when done.
Let the casserole rest for 10 minutes.
This helps it set up properly.
Cut into squares and serve it warm.