Begin by placing the room temperature unsalted butter and powdered sugar into a mixing bowl. Use an electric mixer to beat them together on medium speed for 2-3 minutes, until the mixture becomes light and fluffy.

Next, incorporate the vanilla and almond extracts into your creamed mixture. Mix on low speed until well combined.

In a separate bowl, whisk together the all-purpose flour, finely ground pistachios, and salt until evenly blended. Gradually add this dry mixture to the wet ingredients, stirring gently with a spatula.

Scoop out tablespoon-sized portions of dough and roll them into balls. Arrange them on a parchment-lined baking sheet and create an indent in each cookie ball. Chill the tray in the refrigerator for 30 minutes.

Preheat your oven to 350°F (175°C). Once the dough has chilled, place the baking sheet in the oven and bake the cookies for 12-14 minutes, or until the edges are lightly golden.

After the cookies cool, fill each thumbprint with creamy pistachio cream or pistachio butter and sprinkle chopped pistachios over the top.