Sift the flour into a large bowl, then add the cold cubed butter. Using your fingertips or a food processor, rub the butter into the flour until the mixture resembles coarse breadcrumbs—this creates pockets of butter that will make the crust flaky. Stir in the finely grated cheddar cheese and salt. Add the ice-cold water a little at a time, mixing gently with a knife until the dough just comes together without overworking it. Wrap the dough in plastic wrap and refrigerate for 20 minutes to relax the gluten and make it easier to roll out.

Roll out the chilled dough from Step 1 to about 1/8-inch thickness and carefully line an 18cm tart tin, pressing it gently into the corners and sides. Trim any excess pastry from the edges. Chill the lined tin in the freezer for 10 minutes (or the fridge for 20 minutes) to prevent shrinking. Meanwhile, preheat your air fryer to 180°C/375°F. Line the pastry with parchment paper and fill with baking beans to weigh it down. Bake for 10 minutes, then carefully remove the parchment and beans, and bake for an additional 2 minutes until the crust is set but not fully colored.

While the crust is blind baking, arrange the bacon lardons in a single layer in the air fryer basket and cook at 180°C/375°F for 6 minutes until crispy. In a jug or bowl, whisk together the room-temperature eggs, milk, and double cream until well combined. Stir in the Dijon mustard and freshly ground black pepper, whisking until smooth. I find that letting the cream sit out for a few minutes before whisking makes the custard silkier and more integrated.

Remove the partially baked crust from Step 2 from the air fryer and let it cool slightly. Spoon the cooked bacon from Step 3 evenly over the pastry base, then sprinkle the shredded cheddar cheese over the bacon. Gently pour the custard filling from Step 3 over the bacon and cheese, filling almost to the rim. Place the tin back into the air fryer and bake at 160°C/300°F for 30-35 minutes. After about 20 minutes, check the quiche—if the top is browning too quickly, loosely cover it with a piece of foil to prevent over-browning while the center finishes cooking.

When the quiche is golden and the custard is just set with a slight jiggle in the very center, remove it from the air fryer. Let it rest in the tin for 10 minutes before removing—this allows the filling to set further and makes it much easier to slice cleanly. I like to run a thin knife around the edge before unmolding to prevent any sticking.