Meanwhile, in large heatproof bowl, mix cocoa and remaining chopped chocolate; reserve. In 1-quart heavy saucepan, heat half-and-half over medium-high heat until almost boiling. In medium heatproof bowl, beat sugar, egg and egg yolks with whisk until pale yellow. Slowly beat in half of the hot half-and-half, then stir egg mixture back into remaining half-and-half in saucepan. Reduce heat to medium. Heat mixture just to boiling. Cook, beating with whisk, about 1 minute or until thickened. Pour through sieve into reserved cocoa mixture; beat with whisk until smooth. Pour into crust; refrigerate 30 minutes.