To cook Quorn frozen lasagne, follow the instructions provided on the packaging. Generally, it involves preheating the oven to a specified temperature (usually around 200°C/400°F), removing the packaging, and placing the frozen lasagne in the oven. Bake it for the recommended time, typically around 40-45 minutes, or until it's heated through and the top is golden and bubbling. It's essential to check the specific instructions on the package for accurate cooking times and temperature recommendations.