Cream butter and powdered sugar together using a stand mixer.
Mix in vanilla extract and water.
Add flour, pecans, and salt. Mix until well combined.
Shape dough into a flat rectangle, then wrap in plastic wrap. Chill dough in refrigerator for at least 1 hour.
Preheat oven to 250°F (120°C).
Divide dough into 48 equal pieces (see note below), then shape each piece into a ball. Place cookies on baking sheets, spacing them at least 1 inch apart.
Bake cookies for 50 to 60 minutes, or until cookies are very lightly browned on bottom (tops of cookies should not be browned).
Let cookies cool on baking sheets for 15 to 20 minutes.
Place about 2 cups of powdered sugar in a bowl. Gently roll cookies in sugar, coating all sides of cookie. Transfer cookies to a baking rack.
Once the cookies have cooled completely, roll them in the powdered sugar a second time. (Add more powdered sugar to your bowl, as needed).
Serve cookies immediately, or store in an airtight container. Enjoy!
Notes
Pecans - You want to finely chop the nuts (using either a food processor or a nut grinder, or by hand), not completely pulverize them into a flour or paste. You'll need about 8 to 9 ounces (227 to 255 grams) of pecan halves or pieces to get 2 cups.Chilling the Dough - Don't forget to chill the dough! The cookies will lose their shape and melt together in the oven if you skip this step.Shaping the Cookies - To speed up the cookie forming process, shape the dough into a flat rectangle before refrigerating. Once the dough is chilled, use a knife to divide the dough into 48 equal pieces. For example, I divided my dough into 4 long rows, then I divided each row into 12 equal pieces (4 x 12 = 48).Baking the Cookies - If you need more than one baking sheet for the cookies, you can put both in the oven at once. Just remember to rotate the pans about halfway through.More Tips - Make sure to read the info before this recipe card for helpful tips, step by step photos, recipe variations, and more!