How to Make It
Make the cinnamon swirl In a medium bowl, whisk the confectioners’ sugar with the flour and cinnamon. Add the egg whites, butter and vanilla and whisk until smooth. Let stand at room temperature for 1 hour, until thickened.
Make the pancake batter Preheat the oven to 350°. Spread the pecan pieces in a pie dish and bake for about 10 minutes, until toasted and fragrant. Let cool completely, then finely chop.
In a medium bowl, whisk the flour with the brown sugar, cinnamon, baking soda and salt. In a large bowl, beat the eggs, then whisk in the buttermilk. Add the dry ingredients in 3 additions, mixing until just combined each time. Whisk in the melted butter until no streaks remain.
Make the maple glaze In a medium bowl, whisk the confectioners’ sugar with the milk, maple syrup and salt until smooth.
Scrape the cinnamon swirl into a pastry bag fitted with a plain 1/4-inch tip. Heat a griddle or cast-iron skillet and grease it lightly with vegetable oil. For each batch of pancakes, gently dollop 1/4-cup mounds of batter on the hot griddle and spread them to 4-inch rounds. Cook over moderately low heat until the tops are set, about 2 minutes. Sprinkle each pancake with 1/2 teaspoon of the toasted pecans, then pipe a cinnamon swirl onto each one, leaving a 1/2-inch border. Cook for 1 minute, flip the pancakes and continue cooking until golden, about 2 to 3 minutes longer. Transfer to a platter and keep warm while you cook the remaining pancakes.
Drizzle the pancakes with the maple glaze, sprinkle with the remaining pecans and serve.