Preheat the oven to 350 F. Line a 12 cup muffin pan with paper liners. In a medium bowl, whisk together flour, salt, and baking soda. In a large bowl, mix together butter and sugar until fluffy.
Add in the egg and vanilla extract until smooth. Add in the flour mixture, and mix until it is fully combined. Fold in the sprinkles. Evenly divide the cookie dough between the paper liners. Bake for 12-15 minutes.