1. Prepare the filling: Process 200 g of the pistachios in a food processor until they turn into very fine crumbs. Coarsely chop the remaining pistachios and set them aside.

2. In a large bowl, combine the finely ground pistachios, almonds, powdered sugar, corn starch, salt, softened butter, vanilla extract, egg and egg yolk. Whip with a hand mixer for approximately 2-3 minutes until fluffy. If the mixture seems too thin to spread, add a little more cornstarch.

3. Make the simple syrup, in a small saucepan, combine the granulated sugar and water. Heat over low heat, stirring until the sugar has dissolved. Allow to cool slightly.

4. Cut the croissants in half lengthwise and brush both cut sides with the simple syrup.

5. Fill a piping bag with the pistachio filling and evenly apply about ⅔ of the filling on the bottom halves of the croissants.

6. Place the tops of the croissants on and spread the remaining pistachio mixture on top. Sprinkle with the chopped pistachios.7. 8. Place the croissants on a lined baking sheet and bake in the oven for approximately 12-15 minutes until crispy.

7. Let cool slightly before serving, dusted with confectioner’s sugar if desired.