Preheat the oven to 375F (190C) convection (350F/177C conventional) and grease a 6" square cake pan (or as many as you have since you’ll need six layers) .

In a large bowl, combine the almond flour, the 1/2 cup of granulated sugar, salt, vanilla extract and whole eggs. Beat the mixture for 2-3 minutes, at high speed, until the color lightens and the batter looks fluffy.

In a separate bowl, beat the 1/4 cup of granulated sugar with the egg whites, at medium high speed, just until stiff peaks form, 1-2 minutes. Don't over-whip (if you do, see the troubleshooting section).

With a clean spatula, gently fold 1/3rd of the egg whites into the batter until it's fully incorporated. Fold in the second 1/3rd of the egg whites into the batter and then the last 1/3rd.

Sift half of the flour over the batter, gently fold it in just until it's combined and then repeat with the second half. Pour the melted butter around the edge of the bowl and gently fold it in until it's fully incorporated.

Pour 1/6 of the batter into the prepared pan (about 3.5oz) and use an offset spatula to spread it evenly. Bake the cake for 7 seven minutes, on the middle rack, just until it releases from the edge of the pan a little and the cake springs back when you press on it.

Invert the cakes onto a flat surface and then repeat with the rest of the batter. You should get 6 thin layers total.

Brew the coffee and mix it with the sugar until the sugar dissolves. Set it aside to cool completely.

Place the chocolate in a medium, heat safe bowl. Heat the cream in a small saucepan, over medium-low heat, just until it's simmering (not boiling).

Pour the hot cream over the chocolate, cover the bowl and let it sit for 2 minutes. Stir the chocolate until the cream is fully incorporated. Cover the bowl and allow the chocolate ganache to cool completely to room temperature.

Place the sugar and water in a medium saucepan and swirl the pan until the sugar is fully immersed in water. Place the saucepan over medium heat until the sugar dissolves and comes to a gentle simmer. Lower the heat to low and place the lid on the pan and allow the mixture to simmer for a couple minutes. 

Meanwhile, place the egg yolks in the bowl of a stand mixer, fitted with the whisk attachment, and turn the mixer up to high speed. Let it whip while the sugar is done cooking.

Use a candy thermometer to see when the sugar reaches 240F (116C), then lower the mixer to medium speed and slowly drizzle the hot sugar syrup into the thick and foamy egg yolks, while they are whipping. Turn the mixer back up to high speed and let it whip for 5-10 minutes, until the yolk mixture is very pale and fluffy and is cool to the touch or no longer warm.

Turn the mixer back down to medium speed and add in the butter, 2 Tbsp of butter at a time, mixing until each chunk is fully combined and the buttercream looks smooth and creamy.

Scrape the sides and bottom of the bowl, add in the vanilla, dissolved espresso and salt and turn the mixer up to high speed for 1-2 minutes, just until they're fully combine.

To assemble the cake, place the first layer on a flat surface and brush it generously with the coffee soak. Spread a layer of buttercream, about as thick as the cake layer itself, onto the cake.

Top with another layer of cake and coffee soak and then spread a layer of chocolate ganache, about as thick as the cake. Repeat with the rest of the layers and then smooth out the edges as much as possible. Refrigerate the cake for 2-3 hours to let it set.

Slice the edges off the cake to make them smooth and then with the rest of the buttercream, frost the outside of the chilled cake until it's fully covered. Refrigerate it for about an hour, until the buttercream feels firm, and then make the chocolate glaze.

Place the chocolate and oil in a small aluminum bowl. Place the bowl of chocolate on top of a small simmering pot of water (about ¼ -½ cup of water), to create a double boiler.

Stir the chocolate frequently until it’s smooth and silky. Allow it to cool for about 5 minutes before pouring it on top of the cake. 

Place the cake in the fridge for a few minutes so the chocolate sets.

To get clean slices, run a large serrated knife under hot water and dab the water off. So the chocolate doesn't crack, slowly go back and forth to create grooves into the chocolate before you press down and slice.