Savoy-biscuit Paste

Ingredients

Equipment Needed

• •8-inch (20 cm), 8-cup (1.9 L) tall tube or Savoy mold
• •Electric hand mixer
• •Two large mixing bowls
• •Fine-mesh sieve
• •Broad flexible spatula
• •Digital kitchen scale
• •Wire cooling rack

Instructions

1. 1

   Prepare oven and mold

   Set a rack in the lower-middle of the oven and heat it to 325°F (165°C), or 300°F (150°C) in a fan oven. Brush an 8-inch (20 cm), 8-cup (1.9 L) tall tube or Savoy mold with a thin, complete coat of softened butter. Dredge it with the tablespoon of potato starch, turning the mold until every buttered surface is veiled, then knock out the excess. Prepare the mold before whipping anything; this paste cannot wait once the whites are folded.

2. 2

   Sift the dry mixture

   Whisk the flour and 50 g of potato starch together, then pass them through a fine sieve twice onto a sheet of parchment. They should fall freely with no damp lumps. Modern sealed flour and starch usually need no further drying, but if yours has clumped in a humid cupboard, spread the mixture on a tray in a 225°F (110°C) oven for 10 minutes and cool it completely before sifting. Warm flour would collapse the foam.

3. 3

   Whisk to the ribbon

   Put the yolks and superfine sugar in a large bowl. Beat with an electric hand mixer at medium-high speed for 6 to 8 minutes, scraping the bowl once or twice, until the mixture is very pale, thick, and several times its original volume. Lift the beaters: the mixture must fall in a broad ribbon and remain on the surface for about 3 seconds before slowly leveling. Pâte à Génoise Fine (No. 2376) supplies the book's definition of this stage; it is a reference, not an ingredient in the Savoy paste. If the ribbon vanishes immediately, keep whisking. Add the vanilla sugar and beat just long enough to distribute it.

4. 4

   Beat the whites stiff

   Wash and dry the beaters thoroughly, then beat the whites in a spotless bowl. Begin at medium speed until they are evenly foamy, then increase the speed and beat until they form very stiff, upright peaks while still looking smooth rather than grainy. Stop the instant the peak stands. Grease or a trace of yolk prevents the whites from mounting, so use a clean bowl and beaters; patience, not additives, gives the source formula the froth it requires.

5. 5

   Fold without losing air

   Sift one-third of the flour and potato-starch mixture over the ribboned yolks. Cut down through the center with a broad flexible spatula, sweep across the bottom, and lift the paste over itself while turning the bowl. Repeat with the remaining dry mixture in two additions. The base will become thick and may look alarming. Ça se rattrape: fold in about one-quarter of the beaten whites somewhat firmly to loosen it, then add the remaining whites in two portions with lighter, broader folds. If a dry pocket appears at the bottom, scoop beneath that pocket and lift it through two or three times instead of stirring the whole bowl. Stop as soon as no dry flour or large white streaks remain.

6. 6

   Fill and bake

   Spoon the paste carefully into the prepared mold, filling it no more than two-thirds full so the remaining space receives the rise. Do not bang the mold on the counter; smooth the surface lightly with the spatula and put it straight into the oven. Bake without opening the door for 25 minutes, then test at 30 minutes. It is ready when the top is evenly golden, springs back under a gentle fingertip, and a fine skewer inserted near the center comes out dry, usually after 30 to 35 minutes. If the center still trembles or the skewer carries wet paste, return it to the oven for 5 minutes. A pale, underbaked center sinks as it cools.

7. 7

   Unmold and cool

   Let the cake stand in its mold for 10 minutes, then loosen only where necessary with a thin knife and turn it onto a wire rack. Set it upright and cool completely before cutting, at least 30 minutes; the crumb finishes setting as it cools, and slicing early compresses the very lightness you worked to build. Serve in generous wedges. À table!

Chef Tips

• •Use potato starch, labeled fécule de pomme de terre in a French pantry, not potato flour made from the whole dried potato. The starch is white and powder-fine; equal weight with flour is what gives this biscuit its feather-dry crumb.
• •Weigh the flour and potato starch. Their volumes differ even though their weights are equal, and the book's half-flour, half-fécule balance is structural, not decorative.
• •Room-temperature eggs mount more readily than cold ones. Separate them while cold, when the yolks are less likely to break, then leave both portions covered for about 30 minutes before mixing.
• •Serve the biscuit plain when you want its texture to speak. For a birthday table, put berries or a fruit compote and crème Chantilly alongside so each slice keeps its dry, delicate crumb until it reaches the plate.

Advance Preparation

• •The flour and potato starch can be combined, sifted twice, and kept airtight for a day before baking.
• •Butter and starch the mold earlier on the day of baking, then keep it in a cool place until needed.
• •The mixed paste cannot stand. Bake it immediately after folding or the egg foam will begin to collapse.
• •The finished biscuit can be baked one day ahead. Cool it completely, wrap it airtight, and keep it at room temperature; refrigeration makes the crumb stale more quickly. It can also be frozen whole for up to one month.

Frequently Asked Questions

Nutrition Information

1 serving (about 50g)