1/2 cup butter or margarine
1/2 cup chunky peanut butter
1 cup firmly packed brown sugar
1 large egg
1/2 teaspoon vanilla extract
1 1/4 cups all-purpose flour
3/4 teaspoon baking soda
1/2 teaspoon baking powder
1/2 teaspoon salt
1 cup sweetened flaked coconut
Beat together butter and chunky peanut butter in a large mixing bowl. Gradually add brown sugar, beat until combined. Scrape sides of bowl and beat in egg and vanilla until blended. Set aside.
Sift together flour, baking soda, baking powder, and salt; add to the creamed mixture, stirring well. Fold in flaked coconut.
Divide the dough in half and roll each half into a 1 1/2-inch diameter log. Wrap in wax paper and chill for 3 hours or until firm.
Preheat oven to 350°F (175°C). Lightly grease a cookie sheet.
Cut chilled dough into 1/4-inch slices and place 2-inches apart on cookie sheet. Bake for 8 to 10 minutes or until lightly browned. Transfer cookies to a wire rack and let cool.