Place the chopped sweet potatoes in a steamer basket over a pot of water. Cover and bring to a boil. Allow the sweet potatoes to steam for 15-20 minutes, until they are very tender when pierced with a fork.
Let the sweet potatoes cool slightly and then transfer them to a large mixing bowl.
Preheat oven to 350 degrees F.
Using an electric mixer, beat the sweet potatoes until smooth. Add the milk, honey or pure maple syrup, egg, vanilla, cinnamon, nutmeg, ginger and salt. Mix until well combined and smooth.
Spread the sweet potato mixture into an 8x8-inch baking dish.
In a small bowl, combine the pecans, brown sugar and 1/2 teaspoon cinnamon. Sprinkle topping over the top of the casserole.
Cover the dish with foil and bake for 20 minutes. Remove the foil and bake 20-25 minutes more, until the pecans are lightly toasted and the casserole is hot.