Into a bowl sift together flour, salt, and baking powder. In a large bowl with an electric mixer beat butter until creamy OR nead it with your hands

Gradually add sugar, beating until mixture is light and fluffy.

Add egg and vanilla and beat until combined well. Gradually add flour mixture, beating until mixture just forms a dough.

Cut dough into 1/8-inch-thick slices and arrange slices about 1/2 inch apart on baking sheet. Bake cookies in batches in middle of oven until golden around edges, 10 to 12 minutes, and transfer to a cooling rack.Cookies may be kept in an airtight container at room temperature for 5 days.