Baked Cheese Soufflé with Gruyère and Parmesan

Prepare oven and dish. Heat the oven to 180°C (160°C fan) with a shelf in the middle and the baking sheet on it. Brush the soufflé dish with the softened butter and coat it with the 15 g grated hard cheese, tipping out any excess. The cheesy coating gives the mixture something to grip as it climbs, helping it rise tall and evenly.

Cook the base. Melt the 45 g butter in the saucepan over medium heat, stir in the flour and cook for 1 minute. Slowly whisk in the milk, bring to a simmer, still whisking, and cook for 1-2 minutes until very thick. Cooking the flour first removes its raw taste, and a thick sauce is strong enough to carry the cheese and hold the air from the whites.

Add cheese and yolks. Off the heat, whisk in the salt, paprika, white pepper, nutmeg, Gruyère and remaining hard cheese until smooth. Tip into a large bowl and cool for 10 minutes, then whisk in the egg yolks and parsley. Letting the base cool slightly stops the yolks cooking on contact and keeps the mixture silky.

Whisk the whites. In the spotlessly clean bowl, whisk the egg whites with the cream of tartar on medium-high speed for 3-4 minutes until glossy and holding stiff peaks that stand straight up. Cream of tartar is mildly acidic, which strengthens the egg proteins so the foam is stable and less likely to collapse. Even a trace of grease or yolk will stop the whites from whipping.

Fold gently. Whisk a quarter of the whites into the cheese base to loosen it, then fold in the rest in 2 additions with the spatula, cutting down through the middle and turning the bowl, just until no white streaks remain. Overmixing knocks out the air bubbles that make the soufflé rise, so stop as soon as it looks even. Pour into the dish and run your thumb around the inside rim to make a 1 cm groove, which helps it rise straight up.

Bake until risen. Set the dish on the hot baking sheet and bake for 30-35 minutes, keeping the door closed for the first 25 minutes. It is ready when risen well above the rim, deep golden and only slightly wobbly when nudged, with a thermometer in the centre reading at least 74°C. Opening the door early lets out heat and can make the soufflé sink before its structure sets.

Serve immediately. Using oven gloves, carry the soufflé straight to the table and spoon it out from the centre towards the edges. As it cools, the air inside contracts, so it begins to sink within minutes; that is normal, but it is at its most impressive right away.