Whisk the dry ingredients. In a large bowl, whisk together the flour, brown sugar, baking powder, baking soda, cinnamon, and salt until fully combined and no clumps of brown sugar remain.
Whisk the wet ingredients. In a separate medium bowl, whisk the buttermilk, eggs, melted (cooled) butter, maple syrup, and vanilla until smooth and uniform.
Combine. Pour the wet ingredients into the dry. Stir gently with a whisk or spatula just until no streaks of flour remain. A few lumps are fine — do not overmix.
Rest. Let the batter rest for 5–10 minutes while you preheat the pan. This produces noticeably fluffier pancakes.
Preheat the griddle. Heat a non-stick skillet, cast-iron pan, or electric griddle over medium-low heat (about 325°F on an electric griddle). Lightly grease with butter or oil.
Cook the pancakes. Pour ¼ cup of batter per pancake onto the griddle, leaving room between them. Cook for 2–3 minutes, until bubbles form and pop on the surface and the edges look set.
Flip once. Flip carefully and cook the second side for 1–2 minutes, until golden brown and cooked through.
Keep warm. Transfer to a baking sheet in a 200°F oven while you finish the rest of the batter.
Serve. Stack high and serve hot with butter, warm pure maple syrup, and your favorite toppings.