Scrub the sweet potatoes and pierce all over with a fork. Microwave 6 to 7 minutes on high, until they are easily pierced through with a knife or fork (I prefer to bake potatoes, I think they taster sweeter when baked). Slit the sweet potatoes lengthwise and let cool enough so you can handle them, about 5 minutes.
Meanwhile, measure and sift together into a large mixing bowl the whole-wheat flour, all-purpose flour, baking powder, salt and nutmeg. Set aside.
When potatoes are still warm but not too hot to handle, spoon the flesh into a measuring cup. When you have 1 1/4 cups, transfer to the bowl of a food processor.
Add the butter and process until smooth.
Add the eggs and brown sugar and blend until smooth.
Add as much of the milk as the bowl can easily contain and blend.
Spoon the sweet potato mixture and remaining milk into the bowl with the dry ingredients. Mix with a spoon until just combined.
Heat a skillet or griddle lightly coated with vegetable oil on medium heat.
Drop heaping spoonfuls of batter onto the hot griddle.
When pancakes start to bubble, flip and cook until golden.
Serve with Brown Sugar Butter Sauce and toasted pecans.