435g / 15.34ozsuperfine sugar (or other small crystal sugar)
21g / .74ozgelatin sheets, bloomed
14g / .49ozsalt
62g / 2.19ozwater
43g / 1.52ozcornstarch
740g / 1lb10.1ozsugar
620g / 1lb5.87ozheavy cream
21g / .74ozgelatin sheets
For the Praline: In a saucepan, combine the sugar with the water to make a wet-sand consistency. Add the lemon juice to prevent crystallization. Make sure there are no sugar crystals along the inside of the pot and that all the sugar has been hydrated. Cook the sugar over high heat until it reaches 182°C / 360°F.
Meanwhile, toast the nuts in a 160°C / 325°F oven until they begin to have a toasted aroma and a light brown color.
When the sugar has reached the required temperature, stir in the nuts while they are still hot (otherwise the sugar will crystallize).
Turn the heat off and continue to stir until you hear a popping sound.
Pour the praline onto a sheet pan lined with parchment paper.
Once it has cooled, break it up into small pieces (approximately 2.5cm / 1in each) and grind in a robot coupe until sandy in texture (do not grind to a paste).
Reserve in an airtight container. It can keep for up to 2 weeks.
For the Praline Crust: Combine the praline and almond paste in the bowl of an electric mixer fitted with the paddle attachment. Mix on medium speed until uniformly combined, about 3 minutes.
Pour in the chocolate and then the butter. It is crucial that they not be hotter than indicated, otherwise the ingredients (especially the fat) will separate.
Shape into a square, wrap, and refrigerate.
Once cold and firm, roll out 3 mm / .11 in thick in a rectangle 40cm / 15.75in by 60cm / 23.62 in. Transfer to a sheet pan that is as flat as possible.
Place a 40cm / 15.75in by 60cm / 23.62in by 2.5-cm / 1-in Plexiglas frame over the crust. Trim the crust around the inside of the frame so that the crust is inside the frame and the frame is not laying on the crust. The frame should fit inside the sheet pan.
Refrigerate until needed.
For the Frangipane: Line a sheet pan with a nonstick rubber mat. Place a 40cm / 15.75in by 60cm / 23.62in by .5-cm / .19-in Plexiglas frame on top of the mat.
Preheat an oven to 160°C / 325°F.
Mix the almond paste and sugar with a paddle on medium speed until sandy, about 5 minutes. Add the butter and beat on medium speed until the butter has softened and incorporated with the other ingredients, about 5 minutes.
Slowly incorporate the eggs in 4 additions. Scrape the sides of the bowl after every addition.
Add the flour and mix until just incorporated.
Pour the batter onto the prepared sheet pan. Spread the batter evenly inside the Plexiglas frame using an offset spatula, smoothing it out to the top of the frame so that it is an even rectangle. Remove the frame from the sheet pan.
Bake until slightly golden brown around the border, about 8 minutes.
Once cooled, trim the borders so it will fit inside the 2.5-cm / 1-in frame, on top of the praline crust.
Combine the simple syrup and almond extract. Soak the frangipane with the mixture using a pastry brush. Set aside.
For the Praline Mascarpone Cream: Combine the mascarpone with the praline paste and the sugar. Mix over a hot water bath until the sugar is dissolved and all of the ingredients are evenly incorporated and a liquid consistency. Stir in the gelatin and mix until it has dissolved. It is important to use a good-quality mascarpone because more economical ones tend to break when they get hot.
Pour the mixture into the 2.5-cm / 1-in frame lined with the frangipane and praline crust. Remove any excess from the top so that it is even with the top of the frame. Let it set completely in the refrigerator before glazing.
For the Caramel Glaze: Combine the salt, water, and cornstarch. Mix until the cornstarch and sugar dissolve to make a slurry.
Make a dark caramel with the sugar and heavy cream. Combine the sugar with the equivalent of one-quarter of its weight in water and bring to a boil. While it cooks, bring the heavy cream to a simmer and reserve hot. Cook the sugar until it reaches 170°C / 338°F, or until it has a dark amber color. Turn the heat off and slowly stir in the hot heavy cream in increments, using a long whisk. Once all of the heavy cream has been incorporated, turn the heat up to high.
Stir in the slurry and return to a boil to cook the cornstarch and thicken the caramel. When the first bubble appears, it is ready to come off the heat (the bubble means that the starch is cooked through).
Remove from the heat and stir in the gelatin sheets.
Pass the glaze through a fine-mesh strainer and cool over an ice bath.
Refrigerate until needed.
To glaze the cake, melt the glaze over a hot water bath. If necessary, cool the glaze to 19°C / 66°F, pour it over the entire surface of the cake and spread evenly with an offset spatula.
Tap the sheet pan gently to even out the glaze. If there are bubbles on the surface, torch them and they will pop.
Refrigerate and let the glaze set.
Score the desired measurements on the cake (in this case, 1.5cm / .6 in by 5cm / 2in slices), trimming a horizontal border and a vertical border first. Begin measuring at the trimmed borders.
To cut the cake, dip a slicing knife or any other thin knife in very hot water, dry it with a paper towel, then cut, repeating this with every cut in order to get a clean cut. Make sure the knife is at a perfect 90-degree angle to cut straight down. Bring the knife down, then pull toward you to get the cleanest cut.
Reserve refrigerated until needed. Do not cover, because this will cause condensation on the glaze. The cake will last for 2 days.