Éclair au chocolat

Cook the panade. Bring the water, 125 ml milk, 100 g butter, 3 g salt and 5 g sugar just to the boil; add all the flour at once and beat over the heat until a smooth ball forms and a thin film appears on the pan. Use Heavy saucepan and sturdy spatula. Work at medium heat. Allow 5 minutes. The panade forms one smooth ball, pulls cleanly from the sides and leaves a thin film on the base of the pan. Drying the panade removes enough moisture to accept the egg without becoming slack. Keep hands clear of steam and the hot saucepan.

Add the egg by texture. Transfer the hot panade to a bowl and stir it for about 2 minutes to release excess steam, then add the 250 g beaten pasteurized egg in several additions over the remaining time, stopping when the paste is glossy and forms a thick V from the paddle. Use Mixer bowl with paddle or sturdy spatula. Work at off heat. Allow 8 minutes. The finished choux paste is glossy and falls in a slow, thick V from the paddle or spatula without running flat. Gradual egg addition controls the final water content of the choux paste. Use pasteurized egg and keep unused egg refrigerated at 4 °C or below.

Pipe ten even shells. Fit a 15 mm star nozzle and pipe ten straight 12 cm lengths on a lined tray, spacing them well apart. Use Piping bag with 15 mm star nozzle and lined tray. Allow 7 minutes. Ten evenly thick 12 cm strips are piped with clean ridges and enough space to expand without touching. Consistent diameter gives similar baking and internal cavities. Keep the tray clean and free of raw-egg drips around its edges.

Bake and dry the choux. Bake in a fully preheated oven without opening the door during the first 25 minutes; continue until the shells are deeply golden, then pierce each at one end and return them to the switched-off oven with the door ajar for the final drying period. Use Conventional oven. Work at 190 °C oven, then residual heat. Allow 35 minutes. Target 190 °C. The shells are deep golden, feel light for their size and sound hollow when tapped; the interior is dry rather than gummy. A dry shell resists collapse and keeps the filling from soaking through immediately. Use oven gloves and release steam away from the face when opening the oven.

Cool the shells completely. Move the baked shells to a wire rack and leave them unfilled until completely cool. Use Wire cooling rack. Work under room temperature conditions. Allow 30 minutes cooling. The shells are fully cool, dry and firm before any custard is piped inside. Warm shells would soften the custard and create condensation. Do not fill warm shells with chilled custard.

Cook the pastry cream thoroughly. Whisk the pasteurized yolks, 100 g sugar and cornstarch smooth; bring the 500 ml milk to steaming, whisk it gradually into the yolk mixture, return everything to the saucepan and cook while whisking until it bubbles throughout and reaches at least 82 °C, then keep it bubbling for 1 minute. Use Saucepan, whisk and food thermometer. Work at medium heat. Allow 7 minutes. Target 82 °C. The cream bubbles across the surface, reaches at least 82 °C and is thick enough for the whisk to leave clear tracks that close slowly. A full starch cook gives a stable pipeable pastry cream and thoroughly heats the egg mixture. Avoid splashing hot custard and verify the centre of the mixture with a clean food thermometer.

Finish and cool the chocolate custard. Off the heat, melt in 120 g dark chocolate and 30 g butter, then spread the custard in a shallow clean tray, cover its surface and cool it promptly before refrigerating until it reaches 4 °C or below. Use Shallow tray, spatula and refrigerator. Work under cold conditions. Allow 20 minutes cooling; 60 minutes refrigeration. Target 4 °C. The custard is smooth, uniformly chocolate-coloured and chilled to 4 °C or below with no warm centre. Shallow cooling lowers the temperature quickly and prevents a skin under the covering. Keep cooked custard at 4 °C or below after chilling and do not leave it at room temperature for more than 2 hours in total.

Make a smooth glaze. Heat the cream and glucose just to steaming, pour over 150 g dark chocolate, wait 1 minute, then stir from the centre until smooth and fluid enough to coat without running off. Use Small saucepan and bowl. Work at low heat. Allow 3 minutes. The glaze is glossy and flows in a thick ribbon that settles into an even layer without separating. A gentle emulsion gives a clean top coating without overheating the chocolate. Keep water and steam out of the chocolate bowl.

Fill, glaze and chill. Whisk the cold pastry cream briefly until smooth, pipe it through two or three small holes into each completely cool shell until evenly filled, spread or dip a neat strip of glaze over the top, then refrigerate the finished éclairs before serving. Use Piping bag, small plain nozzle and refrigerator. Work under cold conditions. Allow 15 minutes chilling. Target 4 °C. Each éclair feels evenly filled from end to end, the glaze sits in a clean strip on top, and the finished pastry is chilled to 4 °C or below. Even filling avoids hollow gaps while the short chill firms the glaze. Refrigerate finished éclairs promptly at 4 °C or below and keep them chilled until serving.