In a large bowl, whisk together the flour, brown sugar, baking powder, salt, and cinnamon.
In the blender: For the best batter texture, add the milk, mashed sweet potato, egg, and melted butter to a blender jar. Blend for 30 seconds until smooth. This distributes the sweet potato evenly throughout the wet ingredients and eliminates any lumps.In a bowl: measure the cooked sweet potato into a measuring cup, then add it to a bowl. Mash it well until few lumps (or none) remain. Add the milk, eggs, and melted butter, and mix until combined. If needed, press the back of the fork against the sides of the bowl to break up any larger chunks.
Pour the wet mixture into the bowl with the dry ingredients and gently mix from the outside in until combined. Stop when no visible flour remains. The batter is thick but scoopable.
Cook the pancakes
Heat a non-stick pan over medium heat. Once hot, grease it with oil or butter. Immediately pour ¼ cup of batter per pancake and use the back of the scoop to spread it. Cook the first side for 2 minutes. When the edges begin to look defined and bubbles form on top, flip them over and cook the other side for 2 more minutes. Avoid pressing the pancakes with the spatula; it makes them dense by removing the air bubbles inside that make them fluffy.
Remove the pancakes and serve as you go, or keep them warm on a plate covered with a kitchen towel, or in the oven at 200F while you cook the rest. Serve them warm with your favorite syrup and toppings. ite syrup and toppings.
Storage
Refrigerate cooled pancakes in an airtight container or zip bag for up to 4 days, or freeze them for up to 3 months. Reheat in the microwave in 30-second increments, or toast them.
To use canned yams (in syrup): Drain canned yams very well before mashing and measuring.
To use plain pureed sweet potato (like a jar of baby food): Since it's thinner (more liquid) than traditional mashed sweet potato, start with 2 tablespoons less milk (1 cup - 2 TB) and add the rest as needed until the batter is thick but scoopable.