Preheat the oven to 350 F. In a medium bowl, whisk together flour, salt and baking soda. In a large bowl, mix together butter and sugar until fluffy. Add in egg and vanilla extract and mix until smooth.
Add in the flour mixture and mix until it is fully combined. Use a cookie scoop to place cookies onto a large ungreased baking sheet at least 2-inches apart. Bake for 10-12 minutes. Let cool completely.
In a large bowl, mix together butter, powdered sugar and vanilla extract until combined. Spread the frosting onto the cooled cookies and decorate with sprinkles.
