In a large bowl, whisk flour, baking powder, salt, cinnamon, and brown sugar until evenly combined.
In a separate bowl, whisk mashed sweet potato with milk, egg, vanilla, and melted butter until smooth.
Pour the wet mixture into the dry ingredients and stir gently until just combined. Do not overmix. Let the batter rest for 5 minutes.
Heat a nonstick skillet or griddle over medium heat and brush lightly with oil or butter.
Scoop about 0.25 cup of batter per pancake onto the hot surface. Cook 2 to 3 minutes until bubbles form on top and edges look set.
Flip and cook 1 to 2 minutes more until golden and cooked through. Adjust heat as needed to prevent burning.
Repeat with remaining batter, adding a little more oil or butter to the pan as needed. Serve warm with butter and maple syrup.
Notes
Make it dairy-free by using almond or oat milk and swapping the butter for oil. For gluten-free, use a 1:1 gluten-free all-purpose flour blend. Add-ins like 0.25 cup mini chocolate chips or chopped pecans are great—fold them in with the batter.