To make the frangipane, combine the butter and sugar in the bowl of a stand mixer fitted with a paddle attachment and cream for 3 minutes until pale and fluffy.
½ Cup Unsalted Butter, ½ Cup & 1 tablespoon Granulated Sugar
Add the pistachio flour and salt in three parts while mixing, alternating with each egg until the ingredients are incorporated evenly.
1 ¼ Cup Ground Pistachios, 2 Eggs, ¼ teaspoon Kosher Salt
Add the flour - mixing to combine. Transfer to a container and refrigerate until ready to use!
1 Tablespoon All-Purpose Flour
Slice the croissant in half lengthwise and brush each interior side of the croissant with simple syrup. *Note - if your croissant is particularly tall (over 4 inches) you'll want to gently flatten the croissant a touch so that the frangipane will properly bake in between the croissant halves. Grocery store croissants are never a problem here, but if you have more of an artisanal croissant from a bakery, this will help! ¼ cup Simple Syrup, 6 Croissants
Pipe a few tablespoons of pistachio cream inside the croissant and place the croissant top half on top. Pipe a few tablespoons of pistachio cream on top and press sliced almonds on top. Put the assembled croissants in the fridge so the frangipane can solidify for a half hour before baking. You can also store them in the fridge overnight to bake off fresh the next morning.
¼ cup Chopped Pistachios
Bake at 350F degrees for 18-20 minutes until the pistachios start to brown. Dust with powdered sugar before enjoying!
¼ cup Powdered Sugar