Step 1: Sift the almond flour and powdered sugar together twice into a large bowl to ensure a smooth texture for the mandarin orange macarons recipe.
Step 2: In a clean bowl, whip the aged egg whites and cream of tartar until soft peaks form, then gradually add granulated sugar until stiff, glossy peaks are achieved.
Step 3: Fold the dry ingredients and mandarin zest into the meringue using the macaronage technique until the batter reaches a lava-like consistency.
Step 4: Transfer the batter to a piping bag and pipe 1.5-inch circles onto a baking sheet lined with parchment paper or a silicone mat.
Step 5: Tap the tray firmly on the counter to release air bubbles and let the shells rest at room temperature for 30-60 minutes until a skin forms.
Step 6: Bake in a preheated oven at 300°F (150°C) for 15-18 minutes, then allow them to cool completely before removing from the tray.
Step 7: Prepare the filling by whisking egg yolks, sugar, and mandarin juice over a double boiler until thickened, then stir in butter and zest and chill.
Step 8: Pipe the chilled mandarin curd onto half of the shells and sandwich with the remaining shells; refrigerate for 24 hours to mature.