Scrub sweet potato under running water. Pat dry. Pierce with fork all over. Place on a microwave safe plate. Microwave at 2 minute intervals until completely soft. Flip sweet potato during intervals to ensure even cooking. A medium sized sweet potato will take about 6 minutes.*
Remove sweet potato skin and mash until smooth. Allow to cool.
Combine milk, eggs, vanilla, and melted butter until smooth. Add in mashed sweet potato and stir until incorporated.
In a large bowl, whisk together flour, sugar, baking powder, salt, nutmeg, and cinnamon.
Add wet ingredients to dry ingredients. Use a spatula to fold mixture together. Mix until there are no longer any dry streaks of flour. Do not worry if mixture is not completely smooth.
Set skillet or griddle to medium heat. Lightly grease with butter or oil. Once warm, pour in 1/3 cup portion of pancake batter. Cook until bubbles begin to form on surface and edges of pancake are set. Flip pancake and cook the other side until lightly browned. Repeat with remaining batter. Adjust heat accordingly if pancakes are browning too fast.
Immediately serve sweet potato pancakes warm with maple syrup, salted butter, and toasted pecans.