Take 1 Joconde slice and spread the base evenly with the Praline Base. Chill in the refrigerator for 10 minutes for the Praline Base to harden.
Invert the Joconde-Praline onto a cake board so that the Praline Base is at the bottom. Brush 1/3 of the Coffee Syrup on to the Joconde. Spread 1/3 of the Mocha French Buttercream on the Joconde then top with the next slice of Joconde. Repeat, ending with Mocha French Buttercream on top. Don't worry about the buttercream oozing out on the sides. Chill the cake in the refrigerator for 30 minutes.
Chocolate Glaze: Melt chocolate (temper the chocolate if you like) and stir in the butter. Set aside for 10 minutes until it's cooled down completely to room temperature (otherwise it will melt the buttercream) and thickened slightly.
Spread the Chocolate Glaze evenly on top of the cake. Set aside (don't chill it unless your kitchen is extremely warm) for another 15 minutes until the Chocolate Glaze has hardened slightly.
Heat a knife by running it under hot water then wipe dry with a tea towel. Trim off the edges (these are baker's slices, you get to eat them first!), heating and drying the knife after every slice.
To cut the cake into small pieces, score the top of the cake with a heated knife first (otherwise the Chocolate Glaze will not cut nicely), then use the heated knife to cut all the way through the cake.
The cake is best served slightly chilled, so do store the cakes in the refrigerator and take them out to warm up for about 5 to 10 minutes before serving.