Rarebit mac 'n' cheese

Preheat the oven to 200oC, gas mark 6.

Melt the butter in a pan over a medium- low heat, then add the flour and stir until a thick paste forms. Cook out the flour for 4-5 minutes, then gradually add the Guinness, whisking as you go until you have a thick, smooth sauce. Gradually add the milk, followed by ¾ of the Cheddar, all of the Parmigiano Reggiano, the Worcestershire sauce, paprika, cayenne pepper (if using) and a good grind or two of black pepper. Stir until the cheese is fully melted. The texture should be thicker than double cream but still very pourable. Leave the sauce over a very low heat until you’re ready to use it.

Part-cook the pasta for 6 minutes in well-salted water. Just before draining, scoop out a mugful of the pasta water and set aside.

Stir the drained pasta into the rarebit sauce and stir in some of the reserved pasta cooking water until it’s your desired thickness (bearing in mind that the pasta will absorb more sauce while it bakes). Transfer to a baking dish (about 31 x 25cm) and top with the remaining Cheddar, then the sage leaves (if using). Bake until golden and bubbling (around 25 minutes).