Place chocolate chips, whipping cream and butter in a medium microwave-safe bowl. Microwave on High 1 minute. Stir until chocolate chips are melted and mixture is smooth. (Note: if needed heat 10-30 seconds more in microwave to melt chips.) Stir in lemon peel. Let cool 5 minutes.
Drizzle ganache over pound cake. Refrigerate until ready to serve. Cut into slices to serve. Serve with remaining ganache.