Preheat the oven to 350 F. In a medium bowl, whisk together flour, salt, and baking soda. In a large bowl, combine butter with sugar until fluffy. Add in the egg and vanilla extract, and mix until smooth.
Add in the flour mixture, mix until it is fully combined. Fold in the sprinkles. Place the powdered sugar into a shallow dish. Roll the cookie dough into balls, then roll each one into the powdered sugar.
Place the cookies onto a large ungreased baking sheet at least 2-inches apart. Bake for 10-12 minutes.
