Use a sharp knife to score the sweet potato. Microwave on high for 10 minutes, or until soft. When cool enough to handle, scoop the potato into a small bowl and discard the skin.
Heat the oven to 375ºF and line a 12 cup standard muffin tin with paper liners.
Add 1 cup of sweet potato along with the eggs, buttermilk, flour, oats, Baking Blend sweetener, baking soda, baking powder, salt, and spices to a blender or food processor, in the order listed. Cover and blend on high 2-3 minutes, scraping down the sides of the blender as needed, until the batter is smooth and all of the ingredients are fully incorporated.
Divide the batter among the prepared muffin cups.
In a small bowl, combine the streusel ingredients. Mix the ingredients together until they resemble coarse, wet sand. Spoon the topping onto each muffin.
Bake for 21-23 minutes, or until the muffins are golden brown and a toothpick inserted in the center comes out clean. Let cool completely.