1. Heat oven to 350°F. Grease 8-or 9-inch square baking pan.
2. Beat butter, brown sugar, egg and vanilla in medium bowl until fluffy; stir in flour. Stir in 1 cup milk chocolate chips and 1/2 cup pecans. Spread batter evenly in prepared pan.
3. Bake 25 to 30 minutes or until lightly browned. Remove from oven. Immediately sprinkle remaining 1 cup chips over surface. Let stand 5 to 10 minutes or until chips soften; spread evenly. Immediately sprinkle remaining 1/4 cup pecans over top; press gently onto chocolate. Cool completely in pan on wire rack. Cut into squares. About 16 squares.