A fun and festive macaron, all decked out in St. Patrick's Day green! These minty treats will remind you of your favorite seasonal fast food treat: the Shamrock Shake!
Set the egg whites aside to come to room temperature.
Measure the almond meal, powdered sugar, and salt into the bowl of a food processor. Process the mixture finely, then sift, discarding any large bits. Set aside.
Measure the granulated sugar in a small bowl.
Add the cream of tartar to the whites, and mix on medium-high speed, using the whip attachment.
When the whites hold soft peaks, start adding the granulated sugar, very slowly, while continuing to whip.
When all the granulated sugar has been incorporated, continue to whip until stiff. Add color.
Add the almond meal mixture to the meringue all at once, and fold together, until the batter drops from the spatula in a long ribbon.
Transfer to a piping bag fitted with a large round tip, and pipe 1 1/2-inch diameter rounds onto parchment-lined baking sheets.
Allow to dry for 45-60 minutes, or until thin, dry membrane forms on the surface.
Preheat the oven to 300 degrees F, and bake the macarons (one sheet at a time) until set (approximately 10-15 minutes). Do not brown.
Allow to cool on the baking sheet, then carefully peel from the parchment and sandwich with filling.
Place the egg whites and sugar in a large metal mixing bowl and set over a pot of barely simmering water.
Cook, whisking occasionally, until the mixture is very warm to the touch and no longer feels gritty when rubbed between the thumb and forefinger (about 5 minutes).
Remove the bowl from the heat and whip on medium-high speed until stiff and glossy and completely cool. (There should be no hint of warmth when you place your hand on the side of the bowl.)
Whip in the butter, a tablespoon at a time. (If the buttercream seems runny, place the entire bowl + whisk in the refrigerator for 10 to 20 minutes, then re-whip.)
Stir in the vanilla and peppermint extracts and transfer to a pastry bag fitted with a 4B tip.
Pipe the buttercream on half the macaron shells and sandwich.
Pipe a small amount of buttercream on the tops of the macarons, and top with a maraschino cherry.