Preheat oven to 350°. Spray 13 x 9-inch baking pan with no-stick cooking spray; set aside.
Cook Olive Oil, sugar and water in 4-quart saucepan over medium-high heat until sugar dissolves. Stir in 2 cups chips and vanilla until smooth with wire whisk. (Batter will be gritty). Let cool 15 minutes. Stir in flour, baking soda and salt with wire whisk. Stir in eggs and pecans. Spread batter into prepared pan.
Bake 35 minutes or until toothpick inserted in center comes out clean. Evenly sprinkle warm brownies with remaining 2 cups chips in single layer. Let stand 5 minutes to soften, then spread over brownies. Cool brownies completely on wire rack.