HEAT oven to 375°F.
COMBINE oats, flour and baking soda. Beat butter, peanut butter and sugar in large bowl with mixer until well blended. Add egg; mix well. Gradually beat in oat mixture until well blended. Stir in raisins.
DROP tablespoonfuls of dough, 2 inches apart, onto baking sheets sprayed with cooking spray. Flatten dough slightly with back of spoon; top each with 1 chocolate piece and additional tablespoonful of dough. Use back of spoon to flatten dough slightly. If necessary, press edges of dough together to enclose chocolate.
BAKE 10 to 12 min. or until golden brown. (Do not overbake.) Cool on baking sheets 5 min. Remove to wire racks; cool completely.
serving size = 1 cookie (30 g)