Cheddar Gougere with Cheese Custard

STEP 1: MAKE THE MUSTARD CRAQUELIN

Beat the softened butter, caster sugar, mustard powder, salt and grated cheddar to a smooth paste, then work in the flour until it comes together as a dough. Roll between two sheets of baking paper to 2 mm, then freeze flat for at least 30 minutes. Cut into 3 cm discs and return to the freezer until the choux is piped. (Alternative: for a separate baked cracker rather than a craquelin lid, roll the same dough to 1.5 mm, cut 3 cm discs, bake at 170C / 340F for 10-12 minutes until deep gold, cool on the tray and place on the filled gougeres at the last moment.)

STEP 2: START THE CHOUX PASTE

Heat the oven to 200C / 400F and line two heavy baking sheets. Bring the milk, water, butter, salt and sugar to a full rolling boil in the saucepan; the butter must be completely melted before the boil, or the fat-to-liquid ratio shifts as the liquid reduces. Take off the heat, add all the flour at once and beat hard until the paste comes together and pulls cleanly from the sides. Return to a medium heat and cook, stirring, for 60-90 seconds to drive off moisture - a thin film forming on the pan base is the signal to stop.

STEP 3: ADD THE EGG AND CHEESE

Transfer to a stand mixer and paddle on low for 2-3 minutes to cool the paste to about 60C / 140F; adding egg to hotter paste scrambles it. Add the beaten egg in five or six additions, letting each fully incorporate, and stop when the paste falls from the paddle in a slow V. You may not need all the egg, as humidity and flour absorbency vary. Beat in the grated Snowdonia cheddar, mustard powder, cayenne and white pepper on low, just until distributed - overworking melts the cheese into the paste and costs you the sharp cheddar hit in the finished shell.

STEP 4: PIPE AND BAKE THE GOUGERES

Pipe 3 cm rounds through the 10 mm plain nozzle, spaced 4 cm apart, and flatten any peaks with a wet fingertip. Sit a frozen craquelin disc on each round now. Bake at 200C / 400F for 12 minutes, then drop to 175C / 350F and bake a further 18-22 minutes until deeply golden and light in the hand; do not open the door during the first 20 minutes. Pierce the base of each shell with a skewer and return to the switched-off oven, door ajar, for 8 minutes to dry the interior. Cool completely on a rack.

STEP 5: MAKE THE OLD WINCHESTER CUSTARD

If using gelatine, soak the leaf in cold water until soft. Bring the milk and cream to just below a simmer. Whisk the yolks and cornflour to a smooth paste, pour on a third of the hot liquid while whisking constantly, then return everything to the pan. Cook over a medium heat, whisking without pause, until the custard thickens and just reaches a bubble at about 82-84C / 180-183F, and hold it there for 30 seconds to cook out the cornflour. Off the heat, add the grated Old Winchester in three additions, whisking each until fully melted - all at once drops the temperature and leaves the custard grainy.

STEP 6: SEASON AND CHILL THE CUSTARD

Whisk in the Dijon, nutmeg and the squeezed gelatine if using. Season with white pepper and salt, tasting first, because between two aged cheeses there may be enough salt already. Pass through a fine sieve, press cling film directly onto the surface and chill for at least 3 hours. Beat smooth with a spatula before filling; if it has set too firmly, slacken with a tablespoon of cold cream.

STEP 7: SET AND BLEND THE WORCESTERSHIRE GEL

Whisk the Worcestershire sauce, water or ale, brown sugar, sherry vinegar and agar together cold in a small pan. Bring to a boil, whisking, and hold at a full boil for 2 minutes - agar does not set unless it is properly boiled, and undershooting this is the single most common cause of a gel that never firms. Pour into the shallow tray and chill until fully set, about 45 minutes. Cut the set gel into rough pieces, blend to a smooth fluid gel with a stick blender, pass through a fine sieve and transfer to a small piping bag or squeeze bottle.

STEP 8: FILL AND FINISH

Make a small hole in the base of each cooled gougere with the 6 mm nozzle. Pipe in the cheese custard until the shell feels heavy and just begins to resist, roughly 12-15 g per shell. Pipe a small dot of Worcestershire gel into the centre of the custard as you withdraw the nozzle, so the sauce sits inside the bite rather than on the outside of it. Add a fine shaving of Old Winchester and serve within 30 minutes - the shell is at its best in the first quarter of an hour after filling. To reproduce the larger portion served on the broadcast, pipe 5 cm rounds, extend the second bake by 6-8 minutes and expect the yield to fall to about 10.