Salted Maple WalnutMacarons

"I first tried my hand at making macarons during the 2011 holiday season. I had a marathon day during which I made six different kinds of macarons (with six different fillings) and have been hooked ever since. I love trying new flavors and this particular contest inspired the maple flavor. I adapted the recipe for the shells from Serious Eats, "How to Make Macarons" (posted by Robyn Lee 10/24/07). I've found that combining/processing the confectioners sugar and almond meal together in a food processor helps keep the ground almonds from getting pasty. The buttercream recipe was borrowed from Les Petits Macarons, Kathryn Gordon & Anne E. McBride. I've converted/adjusted the indgredients to metrics to be consistent with the macaron recipe. Because the maple buttercream can be a very sweet filling for an already very sweet cookie, I increased the salt in the buttercream...."