Preheat the oven to 190°C/375°F/gas 5. Grease four ramekins and set aside. Place the milk, butter and flour in a saucepan and whisk together until smooth and thickened. Cook the flour out for a few more minutes over a low heat, then stir in the seasonings. Whisk in the cheeses until thoroughly combined and smooth. Whisk together the egg yolks and whisk into the cheese mixture. Beat the egg whites to stiff peaks, then stir 2 tbsp into the cheese mixture. Fold in the remaining egg whites with a metal spoon, using a figure-of-eight motion to retain the air. Spoon the mixture into the ramekins. Run your thumb around the rim of the ramekin to enable the soufflé to rise straight up. Place on a baking sheet and cook for 15-20 minutes or until the soufflé is well risen, golden on top with a hint of wobble. Cooking tip It's hard to be precise about cooking timings as ovens are different and some will cook faster than others. A keen eye on the soufflé is often a better guide. Vary the cheeses - try a good strong Cheshire or Lancashire cheese instead of the Cheddar for a lemony freshness. Goat's cheese could be crumbled in to the soufflé.