Preheat oven to 350 degrees F. Oil two 7.9inch (20cm) springform cake pan and line the bottom with baking paper.
Start by making the filling: place the cream in a saucepan and heat until it is nearly boiling. Remove from heat and add the chocolate all at once.
Whisk until the chocolate is melted and the mixture is silky and smooth. Add the juice, mix well; refrigerate it, well covered, for 4-6 hours or until set.
To make the cupcakes, in a medium sized mixing bowl, sift together flour, cocoa powder, baking powder, baking soda and salt.
In a large mixing bowl, using a mixer on medium speed, beat oil, butter, granulated sugar and vanilla, until creamy, about 2 minutes.
Beat in eggs, one at a time, until well combined. Beat in 1 cup melted chocolate chips until combined.
Reduce mixer speed to low and beat in flour mixture, alternating with buttermilk, until well combined, about 2-3 minutes.
Divide batter into cupcakes pans. Bake 20 minutes, or until just set, and a toothpick inserted into cake comes out with moist crumbs attached.
Cool for 5 minutes before transferring to wire racks to cool completely.
