PREHEAT oven to 300º F. Line 9-inch-square baking pan with foil.
Grease bottom and sides.
HEAT 1 1/2 cups morsels, butter and water in medium, heavy-duty saucepan over low heat, stirring constantly, until morsels and butter are melted and mixture is smooth. Stir in cocoa until smooth. Remove from heat.
BEAT eggs and sugar in medium mixer bowl until thick, about 4 minutes. Stir in vanilla extract. Fold 1/3 of egg mixture into chocolate mixture. Fold in remaining egg mixture, one half at a time, until thoroughly incorporated. Fold in pecans. Pour into prepared pan.
BAKE for 35 to 40 minutes or until risen in center and edges start to get firm and shiny (center may still move and appear underbaked). Cool completely in pan on wire rack (center may sink slightly). Cover; refrigerate for 4 hours or overnight.
PLACE cream in small, uncovered, microwave-safe dish. Microwave on HIGH (100%) power for 25 to 30 seconds. Add remaining 1/2 cup morsels. Let stand for 2 to 3 minutes; stir until chocolate is melted.
SPREAD ganache over chilled brownie. Refrigerate for 30 minutes. Using two opposite sides of foil, carefully lift the entire brownie out of the pan and place on cutting board. Carefully peel away foil from brownie. Cut into bars. Store in tightly covered container in refrigerator.