Beat butter at medium speed with an electric mixer until creamy; gradually add sugars, beating well.
Add egg and vanilla, beating until combined.
Combine flour, baking powder, and salt; gradually add to butter mixture, beating until blended. Stir in oats and remaining ingredients. Drop by rounded tablespoonfuls onto ungreased baking sheets.
Bake at 375 for 10 minutes or until lightly browned. Cool cookies on baking sheets 1 minute; remove to wire racks to cool completely.