Mix the butter, sugars & vanilla until creamy. Beat in eggs, one at a time. Combine the dry ingredients, stir into the butter mixture and mix well. Fold in the white & milk chocolate chips. Drizzle in the melted semi-sweet chocolate chips stirring to create a marble effect. Drop dough onto parchment lined cookie sheets. Bake at 350°F for 10 – 12 minutes or until golden and set.