Preheat the oven to 350.
In a large pot, use a steamer basket if available, add about 2 cups of water and bring to a boil. Add the sweet potatoes, cover and steam for 10-15 minutes until the
sweet potatoes are fork tender. If not done after 15 minutes, just check every few minutes until a fork mashes them easily.
In a large bowl, add in the maple syrup or brown sugar, orange zest and juice, ginger, and cinnamon. Add in the hot sweet potatoes and mash together with a potato masher, potato ricer, or a food mill. Place the sweet potatoes in a casserole dish and bake for 5-10 minutes.
If making ahead, the sweet potatoes can be cooled at this time and heated just before serving. Still heat at 350 but for 20-25 minutes instead.
While the sweet potatoes are baking combine the streusel: oats, butter, brown sugar, and pecans . Mash together with a fork, pastry blender, or it is most fun with clean hands.
When the sweet potatoes are hot to the touch in the center, sprinkle the topping evenly on top. Bake for 5-10 more minutes until the streusel is hot and slightly crispy.
