Combine butter, pastry flour, 1 cup confectioners' sugar, pecans, water, and vanilla extract in a bowl; mix until well combined.

Preheat the oven to 325 degrees F (165 degrees C) and line a baking sheet with parchment paper.

Roll dough into 1 tablespoon-size balls and set on the prepared baking sheet.

Working in batches, bake in the preheated oven until bottoms are light golden brown but tops are still pale, about 14 minutes.