I have two suggestions - one is pretty easy, the other is more complicated. The easy suggestion is The Chocolate Oblivion Truffle Torte (page 84), which contains only chocolate, butter, and eggs. The more complicated would be the Chocolate Fudge Cake (pg 60), using Rose’s suggestion from the blog for glazing the Interior of the cake with an optional ganache glaze.
Here are Rose’s directions:
“the perfect solution to making my chocolate cake richer without being denser is to apply a ganache glaze to the interior of the cake. (you are going to LOVE this!)i’ve only done this on a 9 inch layer so you’re going to have to work out the proportions but it’s easy. for a two egg recipe, use 3 ounces/85 grams of bittersweet chocolate 51 to 61% but no higher, and 6 ounces/175 grams of heavy cream. when the cake is baked, as soon as it comes out of the oven, poke deep holes with a wooden skewer all over the cake and brush in half the warm glaze. actually i found the directions i wrote up for the 9 inch layer - While the cake is baking, prepare the glaze: Break the chocolate into pieces and process in a food processor until very fine. Scald the cream (heat to the boiling point. Small bubbles will appear around the edges), and with the motor running, pour it through the feed tube in a steady stream. Process a few seconds until smooth. (Alternatively, grate the chocolate, place it in a small bowl and stir in the scalded cream until the mixture is uniform in color. Transfer the chocolate glaze to a small bowl and keep it warm. When the cake is baked, place it still in the pan on a rack and with a wooden skewer, poke holes all over the top. Use a brush to dabble half of the chocolate glaze onto the cake. It will take about 10 minutes. Invert the cake onto a flat surface, such as a card board round or plate, which has been covered with plastic wrap or waxed paper. Peel off and discard the parchment and poke holes all over. Dabble with the remaining glaze, brushing a little onto the sides of the cake as well. Cool completely, for 1 or more hours, until the chocolate is firm to the touch.”