METHOD

1. Add  Penne to a large pan of boiling water for 7 – 10 minutes (I find 8 minutes works well), or until al dente, stirring occasionally. Drain, rinse with warm or cold water and set aside.
2. Add the butter, flour and milk to a saucepan and using a balloon whisk, stir continuously until the mixture thickens to a smooth sauce. Add ground pepper to season.
3. Preheat the grill to hot.
4. Remove the sauce from the hob, add 100g of the cheese and stir until well combined and melted.
5. Add Penne to the sauce and mix well. Transfer to a deep, suitably-sized ovenproof dish.
6. Sprinkle the remaining cheese over and place the dish under the pre-heated grill for a few minutes until the cheese is browned. Serve immediately.