Step 1

Preheat your oven to 450°F

Step 2

Grease a 13" x 18" rimmed baking sheet and then line it with a piece of parchment paper that fits snuggly inside it. Make sure that the parchment paper adheres evenly to the entire surface of the pan, especially around the edges.

Step 3

Have a second piece of parchment paper of the exact same size ready to line the pan a second time, or prepare a second pan if you have access to one.

Step 4

Sift the almond flour, powdered sugar and flour together over a large mixing bowl. Reserve.

Step 5

Combine the egg whites, granulated sugar and cream of tartar in the bowl of a stand mixer equipped with the whisk attachment. Beat on high speed until light and fluffy and stiff peaks form, about 4 to 5 minutes. Transfer to a bowl.

Step 6

In the bowl of the stand mixer (no need to rinse or wash), combine the sifted almond flour, powdered sugar and flour with the corn syrup and 3 eggs. Beat on medium speed with the paddle attachment until well combined; the batter will be kind of thick and sticky at this point.

Step 7

Add 5 more eggs, one at a time, beating until fully incorporated between each addition, and then continue mixing on high speed for about 5 minutes, or until the batter gets light and airy and almost white in color.

Step 8

Pour in the melted butter and delicately fold it in with a rubber spatula.

Step 9

Add the reserved meringue to this mixture and delicately fold it in with a rubber spatula.

Step 10

Using an offset spatula, spread half of this batter as evenly as possible onto the prepared cookie sheet and bake in the oven for 5 to 7 minutes, or until the top turns golden brown.

Step 11

Turn this cake over onto a clean tea towel as soon as it comes out of the oven but do not remove the parchment paper just yet.

Step 12

Let the baking sheet cool for a minute or two, then grease and line it with parchment paper once again; spread the remaining batter, bake and flip that second cake onto a clean tea towel, just like you did with the first cake.

Step 13

Set aside to cool completely.

Step 14

In a mixing bowl, combine the chopped chocolate, heavy cream and butter and place that in the microwave for 1 minute. Allow to rest for 1 full minute and then stir for 1 minute. If there are still lumps of unmelted chocolate left after that, repeat the process but for 30 seconds this time, and continue doing that until the chocolate is completely melted and the ganache is fully combined without feeling hot to the touch.

Step 15

Let your ganache rest at room temperature until it has a consistency similar to that of buttercream. This could take up to a couple of hours, depending on the ambient temperature.

Step 16

While that ganache is resting, let’s get busy working on the buttercream.

Step 17

Make a batch of Swiss meringue buttercream recipe following the instructions in the post.

Step 18

When the buttercream is ready, dilute the instant coffee powder in the boiling water and add that to the buttercream; mix it in on low speed and then give the cream a good beating on high speed for about 30 seconds.

Step 19

Reserve at room temperature until ready to use.

Step 20

Bring the sugar and water to a boil over medium heat. Stir in instant coffee powder and let this syrup simmer for about a minute then kill the heat and set aside.

Step 21

Grab one of the Joconde cakes and carefully pull on the parchment paper to remove it. Cut the cake exactly in half crosswise and place one of the halves on a large cake board or inverted cookie sheet. Brush the entire surface of the cake generously with the coffee syrup.

Step 22

Now mound a little more than a third of the coffee buttercream right in the center of the cake and spread it evenly, all the way to the edge.

Step 23

Place the other half of the cake you just sliced over this layer and again, brush generously with the coffee syrup. Then, mound the ganache, save for a few tablespoons which you'll use to decorate the cake later, right in the center of the cake and spread evenly all the way to the edge.

Step 24

Repeat the process with the other Joconde cake; remove parchment paper, cut it in half crosswise, place one of the halves over the 2 layers already in place. Brush with syrup, spread about 2/3 of what's left of the buttercream and then add the final layer, top with a thin layer of the buttercream just enough to make the top really nice and smooth. Make sure that you also save a few tablespoons of the buttercream to decorate the cake.

Step 25

Send your cake to the fridge to firm up completely, at least 2 hours, but preferably 4 to 6 hours.

Step 26

Combine the chocolates and oil in a bowl and melt in the microwave in 30 second increments, stirring well for an equal amount of time between each increment, until the chocolate is completely melted. About 3 to 4 trips to the microwave should do the trick. Make sure that the chocolate doesn't get hot, otherwise it'll melt your delicate buttercream on contact.

Step 27

Pour that chocolate glaze slowly right in the center of your cake and then spread it all the way to the edge with a straight metal spatula. Don’t worry if it goes over a little bit, you’ll be cutting that out later. However, try to make that top as smooth and straight as possible. Every little defect will show once the chocolate sets.

Step 28

Send the cake back to the fridge until completely set, ideally about an hour.

Step 29

Take the cake out of the fridge and carefully trim out the edges with a long serrated knife

Step 30

Transfer your cake to a clean cake board and decorate it with the reserved ganache and buttercream. Use either a parchment paper cone or a pastry bag equipped with a fine round tip.

Step 31

Let the cake sit at room temperature at least 4 hours prior to serving. If you were to serve it cold, the ganache and buttercream would be very firm and would not melt in your mouth on contact the way they’re supposed to.