Preheat your oven to 350°F (175°C) and line the baking sheets with parchment paper.

Cream together the softened butter and granulated sugar in a large mixing bowl until light and fluffy, about 3–4 minutes.

Beat in the egg and vanilla extract until fully incorporated.

Whisk together the flour, baking powder, and salt in a separate bowl.

Gradually add the dry ingredients to the wet mixture, mixing until just combined.

Scoop rounded balls of dough onto the prepared baking sheets, spacing them about 2 inches apart.

Bake for 12–15 minutes, or until the edges are lightly golden. Let them cool on the baking sheets for about 5 minutes, then transfer to wire racks to cool completely.

Beat the softened butter for the filling in a medium mixing bowl until creamy.

Add the powdered sugar and pistachio paste gradually, mixing until smooth.

Stir in the vanilla extract and heavy cream, adjusting the cream for the desired consistency.

Turn half of the cooled cookies upside down and pipe or spread a generous amount of pistachio cream filling on the flat side.

Sandwich the remaining cookies flat side down on top of the filling.

Chill the assembled cookies in the refrigerator for about 30 minutes if you desire a firmer filling.

Serve your gorgeous pistachio cream-filled cookies and enjoy!