Make the swirl: In a small bowl, mix the melted butter, brown sugar, and cinnamon. Spoon into a small zip-top bag and snip off a tiny corner for swirling.
Prepare the pancake batter: In a bowl, whisk together flour, sugar, baking powder, baking soda, and salt. In another bowl, whisk milk, egg, melted butter, and vanilla. Combine wet and dry ingredient. Don’t overmix!
Cook the pancakes: Heat a non-stick pan or griddle over medium heat and lightly grease. Pour ¼ cup batter onto the pan. Immediately swirl the cinnamon mixture on top of the pancake batter in a spiral shape. Cook until bubbles form on top, about 2 minutes. Flip and cook another 1–2 minutes.
Serve warm: Optional drizzle of maple syrup, cream cheese glaze, or powdered sugar.
