Heat oven to 350°F.

Grease bottom and sides of 13 x 9-inch pan with shortening or spray with cooking spray.

In 4-quart saucepan, melt 1 cup butter over medium heat; remove from heat.

Mix in granulated and brown sugars, vanilla and eggs until well blended.

Stir in flour, ¾ cup cocoa and the salt until well blended.

Stir in 1 cup each semisweet and white chocolate chips.

Spread in pan.

Bake 30 to 35 minutes or until set.

Cool completely, about 1 hour.

In large bowl, beat powdered sugar, ¼ cup cocoa, ¼ cup butter and enough of the milk with electric mixer on low speed until frosting is smooth and spreadable.

Spread over brownies.

In microwavable container, microwave ½ cup white chocolate chips and the oil uncovered on High 30 to 60 seconds, stirring once or twice, until thin enough to drizzle.

Place in small resealable food-storage plastic bag; cut off tiny corner of bag.

Drizzle over frosting.

Cut into 6 rows by 4 rows.