Heat oven to 350°F. In small saucepan, combine chocolate chips and syrup. Cook until chips are melted and mixture is smooth. Stir in half-and-half. In large bowl, combine chocolate mixture and eggs; beat until smooth. Stir in pecans and raisins. Pour into pie shell. Bake at 350°F for 30 to 40 minutes or until top is set and knife inserted in center comes out clean. Cool completely. Store in refrigerator. Top with whipped cream and sprinkle with cocoa, if desired.