1. Preheat the oven to 325F. Line two 6-cup loaf pans, each 8-1/2 x 4-1/2 x 2 inches.

2. Combine the butter, oil, sugar, chocolate, milk and 2/3 cup water in a large saucepan and stir over low heat until the sugar dissolves and the chocolate melts. Remove from the heat. Sift together the flour, cocoa, baking powder and baking soda into a bowl. Beat in the chocolate mixture (using a wire whisk means the mixture is less likely to form lumps).

3. Gradually beat the eggs, one at a time, into the chocolate mixture. Pour into the loaf pans and smooth the top with the back of a spoon. Place the pans on a baking sheet and bake for 50 minutes, or until a skewer comes out clean when inserted into the center of each cake. Cool in the pans for 5 minutes. Turn out onto a wire rack; peel off the paper and cool completely, crust-side-up.

4. To make the fudge topping, bring the cream and corn syrup just to a boil in a small saucepan, then remove from the heat. Put the chopped chocolate in a heatproof bowl and gradually add the cream a little at a time, stirring after each addition, until all the cream has been added and the mixture is smooth. Place the bowl into a larger bowl of ice or refrigerate until the mixture has cooled and thickened. Spoon onto the cakes and spread over the top with a flexible metal spatula. It may run a little over the sides.