Preheat oven to 375 degrees F.
Wash potatoes, prick each potato with a fork, all over. Rinse and pat dry. Line a dish with foil. Arrange the potatoes in a 9 x 13 baking dish.
Bake potatoes for 80-110 minutes, flipping potatoes once while baking. Insert a knife into the center of the potato to check for doneness. If they are a little tough, let them back longer. Larger potatoes may take longer (110 mins) while smaller potatoes may only need 80 minutes.
Allow to cool for 10 minutes. Use a knife to cut into the potato. Scoop out the insides and place in medium bowl. Mash potatoes with potato masher or mixer. This will make them easier to measure and whip later.
Preheat oven to 350 F degrees. Measure out 4 cups sweet potatoes and place in large mixing bowl. Add 1+1/2 cup granulated sugar, 1/2 teaspoon salt + a dash of salt and 1 + 1/2 teaspoons vanilla extract. Turn mixer on speed 6-8 and whip while getting eggs beaten. Add beaten eggs, melted butter and cinnamon to bowl. Continue to mix on speed 6-8 for 2 minutes.
Use a baking dish (I used 9 x 11) but have also used both bigger and smaller. Prepare it with nonstick cooking spray or butter. Evenly spread batter into dish.
Bake for 30-35 minutes at 350 degrees F.
Meanwhile, prepare the topping.
In a medium bowl, combine sugar, flour, pecan pieces and melted butter. Stir to combine well.
Once the potatoes are done baking, spread mixture evenly over the top. Return to oven and bake for 10 minutes.
Allow dish to set for 30 minutes before serving.