HEAT oven to 350°F.
BEAT butter, vanilla and sugar in large bowl with mixer until light and fluffy. Add dry pudding mix and cocoa powder; beat until well blended. Add eggs, baking powder, baking soda and salt; mix well. Gradually beat in flour until well blended.
Coarsely chop 1 (4 oz) package of Baker's Semi-Sweet Chocolate. With the other 1/2 package, either grate (using a microplane) or very finely chop up the chocolate. Stir in both semi-sweet chocolates and white chocolate chips.
DROP tablespoons of dough, 2 inches apart, onto baking sheets.
BAKE 10 to 12 min. or until edges are lightly browned. Cool 1 min. on baking sheets; remove to wire racks. Cool completely.