Biscuit Joconde

Ingredients

Almond-Based Foundation

• 375 grams Tant Pour Tant (equal parts ground almonds and icing sugar, finely sifted together)

Egg Components

• 5 whole eggs (room temperature)
• 5 egg whites (room temperature)
• 25 grams granulated (or caster sugar)

Flour & Fat

• 50 grams cake flour (or soft flour, sifted)
• 40 grams unsalted butter (melted and cooled)
• 30 grams unsalted butter (for greasing baking sheet, optional)

Method

Stage 1 - Prepare Parchment & Equipment

1. Line a baking sheet (approximately 40 x 60 centimeters or 18 x 26 inches) with parchment paper.
2. Have a piping bag or palette knife ready for spreading.

Stage 2 - Whisk Whole Eggs with Tant Pour Tant (Primary Aeration)

1. Place 5 whole eggs and 375 grams tant pour tant in the bowl of an electric mixer.
2. Beat at high speed for approximately 10 minutes.
3. The mixture should become pale, thick, and ribboned (when the whisk is lifted, the mixture falls in ribbons on the surface).
4. Volume will increase noticeably.
5. This is the primary aeration step for the biscuit.

Stage 3 - Whip Egg Whites (Secondary Aeration)

1. In a separate, scrupulously clean bowl (any fat will prevent whipping), place 5 egg whites.
2. Using a clean mixer or whisk, beat the egg whites until soft peaks form.
3. Add 25 grams sugar and beat at high speed for exactly 1 minute.
4. The whites should become very stiff and glossy peaks forming.
5. Do not overbeat (grainy texture indicates over-beating).

Stage 4 - Fold Whites into Yolk Mixture

1. Using a flat slotted spoon or rubber spatula, fold approximately one-third of the whipped whites into the ribboned egg-tant pour tant mixture.
2. Blend thoroughly but gently.
3. Add the remaining whites all at once.
4. Fold extremely gently, using a J-stroke folding motion (scrape down the sides, fold up and over).
5. Stop as soon as color is uniform and no white streaks remain (over-folding deflates the foam).

Stage 5 - Add Butter & Flour

1. Using the flat spoon or spatula, fold the cooled 40 grams melted butter into the mixture.
2. It may seem to tighten slightly as butter incorporates, this is normal.
3. Fold just until distributed evenly.
4. Sift the 50 grams flour directly over the mixture.
5. Fold the flour in very gently (this is the last step before baking; minimal mixing prevents deflation).

Stage 6 - Spread on Parchment

1. Immediately transfer the batter to the parchment-lined baking sheet.
2. Using a palette knife (offset spatula), spread the batter evenly to a thickness of approximately 3-4 millimeters.
3. The thickness is critical, too thin and the sponge breaks apart too easily; too thick and it loses its characteristic delicacy.
4. Spread quickly before the batter deflates from standing.

Stage 7 - Bake at Very High Temperature

1. Immediately place into a preheated oven at 250°C (480°F).
2. Bake for exactly 2-3 minutes (the brief time is essential).
3. Do not open the oven door to check; the biscuit bakes very quickly.
4. Watch through the oven window if possible.

Stage 8 - Test for Doneness

1. At the 2-minute mark, touch the sponge gently with your fingertips.
2. It should feel just firm and set, not sticky, but still be moist and tender (not dry).
3. The surface should not be browned; it should remain pale or have just the slightest golden tint.
4. If damp to the touch, bake an additional 30 seconds and test again.

Stage 9 - Cool on Parchment

1. Remove the baking sheet from the oven and place on a wire rack.
2. Allow the sponge to cool completely (approximately 15-20 minutes) while still on the parchment and baking sheet.
3. Do not remove the parchment until the sponge has cooled completely (removal of warm sponge tears it).

Stage 10 - Storage Until Use

1. Once completely cooled, the parchment-backed sponge can be left on the parchment until needed.
2. If storing before use, cover loosely with cling film or place in an airtight container.
3. Use within 1-2 days of baking for best texture.
4. When ready to use, peel the parchment away very carefully (sponge is delicate) and cut, layer, or crumble as desired for your mousse cake or dessert assembly.