Shū Aisu (シューアイス, frozen choux ice cream puffs)

Ingredients

Equipment Needed

• •Piping bag (shibori-bukuro) with a plain 1/2-inch tip, or a sturdy zip-top bag
• •Heavy saucepan and stiff wooden spoon
• •Rimmed baking sheets with parchment
• •Wire cooling rack
• •Small skewer or thin knife for venting the shells

Instructions

1. 1

   Ready the oven

   Heat the oven to 425°F/220°C and line two rimmed baking sheets with parchment. Beat the eggs in a small cup so you can add them slowly later. Room-temperature eggs work into the dough smoothly; cold eggs tighten the butter and make the paste sulk a little, which is not fatal but is unnecessary.

2. 2

   Dry the dough

   Put the water, butter, sugar, and salt in a heavy saucepan and bring it to a full boil, making sure the butter is melted. Add the flour all at once and stir hard with a wooden spoon until the mixture gathers into a smooth ball. Keep stirring over medium heat for 1 1/2 to 2 minutes, until a thin film forms on the bottom of the pan and the dough smells faintly nutty. This cooks the flour and drives off extra water, so the eggs can be worked in without turning the paste loose.

   This drying is the first secret. A wet dough bakes up heavy, then freezes chewy. A properly dried dough has the strength to rise and the patience to stay crisp.
3. 3

   Work in eggs

   Move the hot dough to a bowl and stir it for one minute to let the fiercest heat pass. Add the beaten eggs in four additions, mixing well each time before adding more. Stop when the dough is glossy and falls from the spoon in a thick V-shaped ribbon. You may not need every drop of egg. The ribbon, not the number, is the measure.

   Too little egg and the shells stay squat. Too much and they spread before they rise. Add the last egg by spoonfuls and watch the dough, the way we do it here.
4. 4

   Pipe the shells

   Spoon the dough into a piping bag with a plain 1/2-inch tip, or use a sturdy zip-top bag with one corner cut off. Pipe 16 mounds, about 1 1/2 inches wide, leaving room between them. Smooth any sharp peaks with a damp fingertip. The peaks would brown before the shells are done, and this small correction gives each puff a clean shape.

5. 5

   Bake them dry

   Bake for 10 minutes at 425°F/220°C, then lower the oven to 375°F/190°C and bake 18 to 22 minutes more, until the shells are deep golden, firm, and light for their size. Don't open the oven during the first 20 minutes. The oven must set the outside before the lift escapes. Turn off the oven, pierce the side of each puff with a skewer or small knife, and return them to the oven for 10 minutes with the door slightly ajar.

   Choux is hollow because the water inside the dough turns to steam and pushes outward while the egg and flour set around that pressure. The small hole at the end lets trapped moisture leave instead of softening the shell.
6. 6

   Cool completely

   Transfer the shells to a rack and cool them completely, at least 30 minutes. They should feel dry, light, and almost papery. This is not fussiness. Warm pastry melts the ice cream at the seam, and that melted cream refreezes into icy crystals and soggy patches.

7. 7

   Fill and freeze

   Cut each puff across the upper third, or make a neat slit in the side. Fill with about 2 tablespoons of softened ice cream, close the puff, and set it on a parchment-lined tray. Work in small batches, keeping the ice cream in the freezer between rounds. Freeze the filled puffs uncovered for 1 hour until firm, then pack them in an airtight container and freeze at least 3 hours more.

   The first open freeze firms the filling without smearing the shells. The airtight container comes after that, to keep frost away.
8. 8

   Serve frozen

   Serve the shū aisu straight from the freezer, letting them sit 2 minutes only if they are too hard to bite cleanly. Dust lightly with powdered sugar if you like. Three small puffs on a plate are plenty, especially if one is split to show the cream inside. Leave it room.

Chef Tips

• •Use ice cream you would happily eat by itself. The freezer does not improve flavor; it only makes weakness colder. Vanilla, matcha, and chocolate are all at home here, provided the flavor is clean and not buried under syrup.
• •Bake the shells a shade darker than your nerve first suggests. Pale choux is usually damp choux, and dampness is what turns a frozen puff leathery.
• •If using matcha ice cream, choose one that tastes of tea, not perfume. Good matcha reads deep green and faintly bitter against the sweet shell. Tired, olive-colored powder has already given up.
• •Fill only as many as you can handle before the ice cream slumps. Four at a time is not slow, it's sensible. The dish rewards a cool hand more than a heroic one.

Advance Preparation

• •The choux shells can be baked one day ahead. Store them loosely covered at room temperature, then re-crisp at 325°F/160°C for 5 to 8 minutes and cool completely before filling.
• •For faster filling, portion the ice cream into small scoops on a parchment-lined tray and freeze them hard. Slip one scoop into each shell and close it before it softens.
• •Filled shū aisu keep well for up to 2 weeks in an airtight container. After that the flavor is still there, but the shell slowly gives ground to the freezer.

Frequently Asked Questions

Nutrition Information

1 serving (about 39g)