- Preheat your oven to 135 degrees C.
- Put the powdered sugar, almond flour and the pistachios in the bowl of a food processor and process until the pistachios are finely ground. Sift the mixture. No lumps or bigger bites of almonds or pistachios should remain.
- Whisk the egg whites for 2 minutes on high speed. Then add the granulated sugar gradually and beat until you have a dense and creamy mixture. Add in the green and yellow gel food coloring in 6 to 1 ratio until you reach a nice pistachio color.
- Fold in the nuts mixture gradually. Stir delicately until the color is evenly blended.
- Transfer the batter to a pastry bag fitted with a 1.25 cm round tip and pipe 3.8 cm rounds of batter to a baking sheet lined with parchment paper spacing evenly. they are not going to expand much so they can be close to one another.
- Bake the macarons for 13 to 16 minutes. Make sure to rotate the pan after 10 minutes.
- After the shells are cooled for about an hour assemble them with pistachio paste.
Store the macarons in an airtight container and refrigerate them for a night before serving them.