- Fill a large pot of water and place it on medium-high heat. Add in the cubes and peeled sweet potatoes and bring to a boil. Cook until very soft. It will take about 20-30 minutes. Drain and add to a large bowl. - 3 cups mashed sweet potatoes 
- Preheat your oven to 350°F then butter a 9x13 inch pan and set aside.  
- Mash the sweet potatoes then add in the brown sugar, lightly beaten eggs, melted butter, half and half, vanilla extract, ground cinnamon, and salt. Mix until combined.  - 1/2 cup brown sugar, 2 large eggs, 1/4 cup unsalted butter, 1/4 cup half and half, 1 teaspoon vanilla extract, 1/2 teaspoon salt, 1/3 teaspoon cinnamon 
- In a separate bowl, mix together the chopped pecans, flour, ground cinnamon,  brown sugar, salt, and softened butter using a fork or your fingers to create a crumbly streusel mixture. - 1 cup chopped pecans, 1/2 cup all-purpose flour, 1/4 teaspoon cinnamon, 1/2 cup brown sugar, 1/4 cup unsalted butter 
- Spread the sweet potato mixture evenly into the prepared dish, then sprinkle the pecan streusel evenly on top of the sweet potato mixutre.  
- Place the baking dish in the preheated oven and bake for about 25-30 minutes or until the sweet potato mixture is set and the streusel topping is golden brown. Allow the casserole to cool down for a few minutes before serving.