Begin by creaming together the unsalted butter, granulated sugar, and salt in a large mixing bowl until the mixture is light and fluffy, about 3-5 minutes. Next, add the room temperature egg, vanilla bean paste, and optional almond extract, mixing until fully combined and smooth.

In a separate bowl, sift together the all-purpose flour, pistachio flour, and baking powder. Gradually add this dry mix into the wet ingredients, stirring with a wooden spoon or spatula until a cohesive dough forms.

Once your dough is ready, place it onto a sheet of parchment paper. Flatten it slightly, then cover with another sheet of parchment and roll it out to your desired thickness.

Wrap your rolled-out dough securely in plastic wrap and refrigerate it for 1-2 hours or overnight. If short on time, place it in the freezer for 15-30 minutes.

Preheat your oven to 375°F (190°C). Remove the chilled dough and let it rest for a few minutes to soften slightly. Cut out shapes using your favorite cookie cutters and transfer them to a parchment-lined baking sheet.

Bake the cookies for 8-10 minutes, or until they are set and the edges begin to turn golden brown but the tops still appear soft.

After the cookies have cooled completely, decorate them with royal icing or sprinkle sparkling sugar on top before they dry.