Preheat oven to 350°.
Lightly spoon all-purpose flour into a dry measuring cup, and level with a knife. Combine flour and 1/2 teaspoon baking powder in a small bowl, stirring well with a whisk. Place the granulated sugar, brown sugar, butter, peanut butter, vanilla extract, and egg white in a large bowl; beat with a mixer at medium speed until well blended (about 2 minutes). Add flour mixture, 3/4 cup oats, 1/2 cup raisins, and 1/2 cup chocolate chips, stirring until ingredients are well combined. Cover and freeze cookie dough for 10 minutes.
Divide cookie dough into 30 equal portions, shaping each one into a ball. Place the dough balls 2 inches apart on baking sheets coated with cooking spray, and flatten dough balls with the bottom of a glass. Bake the dough balls at 350° for 15 minutes. Remove the cookies from pans, and cool completely on wire racks.