Peel and dice the sweet potatoes. Place the sweet potatoes in a large pot filled with water. Bring the water to a boil and then turn the heat to a medium simmer. Cover and simmer until they are tender when poked with a fork.
Drain water and place sweet potatoes in a large mixing bowl. Add eggs, half and half, vanilla, sugar, salt, and butter and mash everything together until smooth.
Pour mixture into a lightly greased casserole dish. Anything around the size of an 8x11" or a deep dish 10'' pie pan will work.
For the topping: Add flour, brown sugar and pecans to a mixing bowl. Add butter and cut in with a fork or pastry blender until well combined. Sprinkle topping over sweet potato mixture.