In heavy 2-quart saucepan over low heat, heat chocolate, heavy cream and margarine, stirring frequently until melted and smooth. Remove saucepan from heat; then add liqueur.
Refrigerate chocolate mixture about 2 1/2 hours or until very thick and of easy piping consistency, stirring occasionally as it's cooling in the frige.
While chocolate is chilling prepare and bake tartlet shells. Cool on wire rack then fill with the chocolate.
This is the most decadent orange chocolate recipe I've ever tried!