A richer, chocolatier version of traditional madeleines, these mini chocolate cakes are covered in a glaze of chocolate ganache. This recipe is based on Chocolate Sweetheart Madeleines from Rose Levy Beranbaum's book, The Baking Bible.
Spray the madeleine pan with baking spray, or grease and then flour the pan, making sure to get in each crevice.
Make the Madeleine Batter
In a medium bowl, whisk together the sour cream, egg, and vanilla. Add the cocoa powder and whisk to combine. It will be slightly lumpy.
In a large bowl or the bowl of a stand mixer with the beater attachment, add the flour, sugar, baking powder, baking soda and salt. Mix on low until well combined.
Add the room temperature butter to the flour mixture. (It needs to be very soft, or you will end up with lumps of butter in your batter.) Mix on low until all the butter is worked into the flour, and it is a coarse, sandy texture.
In three separate additions, add the cocoa mixture to the flour mixture, beating well to combine after each addition.
Halfway fill a large piping bag or other food-safe bag with the batter, and cut off the tip. Pipe the batter into the madeleine pan molds, filling each mold about halfway full. (You can also use a spoon or cookie scoop to fill the molds, just smooth the batter out on top after you fill.)
Bake the madeleines for 14-15 minutes, or until they spring back when lightly pressed. The internal temperature will be 205°F (96°C).
Make Ganache Glaze
While the madeleines are baking, make the glaze. Finely chop the chocolate, or you can use a mini food processor or a rotary cheese grater to process it into very fine pieces.
In a microwave safe container or a small saucepan on the stove, heat the heavy cream until just before it boils.
If you used a food processor, you can slowly pour the cream directly into the bowl of the processor as it is running, and your glaze will be complete.
If you did not use a food processor, add the cream to a heatproof bowl and then, all at once, add the chocolate to the cream. You can poke down all the chocolate so it goes underneath the surface of the cream.
Wait for about 5 minutes, and then vigorously beat the cream and chocolate mixture with a spatula or wooden spoon. You will end up with a very shiny and thin ganache.
Glaze the Madeleines
Once the madeleines are done baking, let them cool in the pan for 5-10 minutes before trying to take them out of the molds. Carefully take them out, using a toothpick to push them from one side if they get stuck.
Place the madeleines on parchment paper and glaze them. You can use a food-only paintbrush if you want to be neat about it, or pour it on with a spout or spoon if you want to be chaotic like me. Once the first layer of glaze has set, you can go back and do another coat if you want.
Store
These madeleines will keep at room temperature for about 3 days, or in the refrigerator about a week, as long as they are in an airtight container.
You can also freeze them in an airtight container for about 2 months.