In a medium bowl, whisk together the flour, baking powder, kosher salt, nutmeg, and cinnamon until fully combined.
In another medium bowl, whisk together the milk, mashed sweet potatoes, melted butter, eggs, and vanilla extract until smooth.
Add the dry ingredients to the wet mixture. Stir just until combined and no dry pockets remain. Do not overmix; the batter should be slightly lumpy.
Lightly spray a nonstick skillet or griddle with cooking spray and place over medium heat (about 350°F if using an electric griddle).
Once hot, pour about ⅓ cup of batter onto the skillet for each pancake. Use the back of a spoon or measuring cup to gently spread the batter into a circle about 4 inches in diameter, if needed.
Cook for 3 to 4 minutes, or until bubbles form on the surface and the edges look set.
Flip and cook for another 3 to 4 minutes, or until golden brown on the other side.
Before starting a new batch, wipe out the skillet with a paper towel and reapply cooking spray as needed. Repeat with the remaining batter.
Serve warm with maple syrup and chopped pecans.