I had something like this in Barbados a couple of years ago. It was delicious and lingered long in the memory.
200-250g shortcrust pastry, rolled to one-third of a cm thick
150g macaroni, cooked
300g mascarpone cheese
150g grated Cheddar plus another 20g to scatter on top
150ml double cream
Salt and pepper
Preheat the oven to 180C/gas mark 5. Grease and line an approximately 25cm x 3cm-deep flan tin with a removable base with the shortcrust pastry and trim the edges.
Line with foil or greaseproof paper and fill with baking beans; bake for about 15 minutes, then remove the greaseproof paper and beans and return the pastry to the oven for another 6-7 minutes, then remove from the oven. Make sure to keep the oven turned on, at 220C/gas mark 7.
Meanwhile, melt the mascarpone in a thick-bottomed pan with the cheddar and bring it to the boil. Add the double cream, season with salt and pepper and simmer for a couple of minutes until it thickens. Whisk the sauce well and mix with the cooked pasta.
Put the macaroni mixture into the flan case and scatter the extra Cheddar on top. Bake for 20-25 minutes until browned.