Directions

1. Preheat oven to 350 degrees. Stir together flour, salt, and baking soda in a small bowl; set aside. Put butter and sugar in the bowl of an electric mixer fitted with the paddle attachment; mix on medium speed until pale and fluffy, about 2 minutes.
2. Mix in egg and vanilla. Reduce speed to low. Gradually add flour mixture; mix until combined. Stir in peanuts.
3. Drop 2 teaspoons of dough on baking sheets lined with parchment paper, spacing about 3 inches apart. Lightly flatten to 1 1/2 inches in diameter. Bake cookies, rotating sheets halfway through, until edges are just golden, about 13 minutes. Let cool on sheets on wire racks.Cookies can be stored in airtight containers at room temperature up to 1 week.