In a medium bowl, sift together the flour, baking powder and salt.
In a large bowl, beat the eggs, brown sugar and maple extract, on medium-high speed with an electric mixer, until the batter is voluminous, light in color and holds its shape when you lift the beater, about 8-10 minutes.
Combine the melted butter and maple syrup.
Gently fold the the flour mixture into the egg mixture in three additions, alternating with the melted butter. Fold just until combined, being careful not to deflate the batter. Make sure to scrape the bottom of the bowl to ensure that all of the flour is combined.
Cover and refrigerate for 30-45 minutes.
Preheat the oven to 350ºF (177ºC). Grease a spherical Madeleine pan* with nonstick spray or melted butter. Dust the pan with a light coating of flour. Tap out the excess flour.
Fill the wells of the Madeleine pan with batter 3/4 full, about 2 tablespoons each, using a scoop**or a spoon. (If you’re using a traditional oval Madeleine pan, fill 3/4 full, about a generous tablespoon of batter in each.)
Bake until golden brown around the edges and puffed in the center, about 10-12 minutes. (Baking time for oval Madeleine pan will be about 7-8 minutes.) Do not over bake.
Cool in the pan for one minute then turn Madeleines out onto a cooling rack to cool completely.
Maple Icing
In a small bowl, whisk together the powdered sugar, melted butter, maple extract and one tablespoon of milk. Add additional milk as needed until your desired consistency is reached, Stir in a pinch of salt to taste.
Brush icing onto the Madeleines with a pastry brush. Apply nuts to the edges of Madeleines. Serve immediately. Madeleines are best served the day they’re baked.