Joconde Sponge Cake, Ribbon Sponge

This is a very light and spongy cake with a decorative element to it. The cake, a Joconde sponge cake, is laid on top of a stencil paste making a Ribbon Sponge. The stencil paste is a just a thin cake layer of a decorative colour or design. Other names for a stencil paste include: tuile paste, hippen masse, tulipe paste, cigarette paste, etc.

Formula: yields enough to fill a half sheet pan
Joconde Sponge: yields 1# 1 oz.
    3.5 oz. (340%)  Powdered almonds
    3 oz. (300%)  Confectioners' sugar
    1 oz. (100%)  Cake flour
    4.75 oz. (480%)  Whole eggs
    3.25 oz. (320%)  Egg whites
    0.4 oz. (2.5t) (40%)  Sugar
    1.25 oz. (120%)  Butter, melted and cooled to room temperature
Stencil Paste:
    3.5 oz. Butter, melted
    3.5 oz. Confectioners' sugar
    3.5 oz. Egg whites
    3.8 oz.  Cake flour
    Food Colouring, as needed


Tools: Silpat, offset spatula, heat resistant spatula, level or flat half sheet pan, pastry comb
*These formulas are adapted from Gisslen, Professional Baking, Ed. 5, pg. 410-411


MOP:
The stencil paste takes at least 15 minutes to scale, so its a good idea to just scale out your ingredients for your stencil paste, and make your stencil paste first. Melt your butter and place in mixing bowl. Add sifted flour and powdered sugar into the bowl. Mix on low speed at first then increase to medium and fully incorporate (this is just like the one-stage cookie method). When incorporated, drizzle your egg whites in making sure to scrape down the bowl as it mixes. Using gloves, if your food colouring is messy, add colouring into the batter. Do not use yellow since the Joconde sponge is a pale yellow but since this is going to be on the outside of your cake do use a complimenting colour to the flavour of your cake filling.


Place your silpat on top of your half sheet pan. If you do not have a silpat you can use a heavily sprayed parchment paper. Spread the batter thinly on the silpat, you'll end up using maybe half of the batter. Smooth out the batter. Use either your finger, pastry comb, offset spatula and scrape off the batter with the tool you picked. Make sure you are scraping away all the way down to the silpat. Freeze until set, when the batter is set you should not be able to move the batter at all when touched.

Other techniques, from Gisslen, that you can use to decorate it:

• Comb with a plastic pastry comb to make stripes, zigzags, wavy lines (as pictured above), or other patterns
• Place a stencil on top of the silpat, spread with a thin layer of the paste, and remove the stencil
• Make an abstract finger-painted design by applying dabs of coloured stencil paste
• Use a palette knife to combine two colours, be careful you do not over-mix because you will just end up with one colour.

Start scaling your ingredients for you Joconde sponge.

Melt butter and let it cool to room temperature. Place sifted almonds, confectioners' sugar, and flour into a your mixer. On low speed add whole eggs in stages using your paddle attachment. Increase speed to high and continue mixing until the batter turns into a pale yellow colour. Transfer to a stainless steel bowl.

Clean mixing bowl throughly and whisk egg whites until foamy. Add sugar and continue whisking on high to a medium-firm peak.

Fold egg whites into egg yolks, fully incorporate both batters. Drizzle butter slowly along the sides of the bowl and fold in the mixture. If you can assist someone else then have them drizzle in the butter while you whisk (like with mayonnaise).

Make sure your stencil paste is set before pouring Joconde over the paste. Use your offset spatula to even out the batter. Use your fingers to clean the sides of the pan before baking.

Bake at 375°F in a convection oven, bake until it is slightly golden in colour. About 7-15 minutes.
In a deck oven bake at 400°F without a rack (10t-10s-6b)