Beat butter at medium speed of an electric mixer until creamy. Add sugars, beating until fluffy. Add eggs, one at a time, beating just until blended.
Combine flour, baking powder, and salt. Gradually add to butter mixture, beating until blended. Stir in vanilla. Stir in white chocolate, candy, and oats. Cover and chill dough 30 minutes.
Drop dough by heaping teaspoonfuls onto parchment paper-lined cookie sheets. Bake at 350° for 8 to 9 minutes or until golden (do not overbake). Cool 5 minutes on cookie sheets; remove to wire racks, and cool completely.