In a bowl, beat the sugar and butter with an electric mixer on medium speed until fluffy, about 4 – 5 minutes. Beat in the chocolate, canola oil, and vanilla. Add eggs, one at a time, beating well after each addition and scraping the sides of bowl as needed. Spoon chocolate mixture into pie shell and chill for at least 3 hours. Top with whipped cream.
3 (1-ounce) squares of unsweetened chocolate, melted and cooled, can be substituted for the cocoa powder and the canola oil.