Wash 4 medium sweet potatoes and bake them in a 375-degree oven until fork tender, about 30-35 minutes. When they are finished cooking slice them open and scrape out the flesh into a large bowl.
Add 1 cup of (regular grandulated) sugar, 1 cup of milk, 2 eggs, 1 teaspoon of vanilla extract and 1 teaspoon of salt. With a potato masher, mash them up just enough—you don’t want to be perfectly smooth.
Now, in a separate bowl, add 1 cup brown sugar, 1 cup pecans, chopped (that means measure a cup of pecans, then chop them), ½ cup flour, and ¾ stick of butter. With a pastry cutter or fork, mash together until thoroughly combined.
Spread the sweet potato mixture into a regular baking dish and sprinkle the crumb mixture all over the top.
Bake in a 400-degree oven for 30 minutes, or until golden brown.