First, cook the pasta. Bring a medium saucepan of water to the boil, add 1 teaspoon of salt and the macaroni, then cook until the pasta is soft all the way through. Drain the macaroni in a colander and then run it under cold water until cooled to room temperature then set aside.
While the pasta is cooking, melt the 50g of butter in a small pan over a medium heat and then add the flour and cook until just starting to brown. Pour in 100ml of the warm milk, whisking until smooth. Whisk in another 100ml of the milk and repeat until all the milk has been added and you have a smooth sauce. Fold in all of the grated Cheddar and 40g of the grated mozzarella. Allow the cheese to sit in the heat of the sauce for a minute, then gently mix until smooth. Stir in 1 teaspoon of salt and a generous amount of freshly ground black pepper. Set aside to cool.
On a lightly floured surface, roll out the pastry to a square about 5mm thick. Press or cut out four 14cm discs.
Lightly grease the insides of the tins with the butter. Line the greased dishes or tins with the pastry discs, making sure that the dough goes right into the edges of each base and avoiding any folds, creases or air pockets. Using a fork, prick the bottoms of the pie cases all over. Do not trim the excess dough from the tops of the dishes or tins to neaten the pies; a rustic look is key here. Place the pastry-lined dishes or tins in the fridge to chill for 15 minutes.
Once the sauce has cooled, stir in the mustard, chives and lemon zest, along with the remaining grated mozzarella. Finally, fold the cooked pasta through the sauce.
Preheat the oven to 200°C fan/220°C/gas mark 7.
Fill each pie case with a quarter of the filling. Cut four small discs of parchment paper and sit them on top of the pies to cover the surface of the filling.
Place the pie dishes or tins on a baking tray in the centre of the preheated oven and bake the pies for 20 minutes. Peel off the paper and scatter the garlic breadcrumbs over the top of the pies.
Lower the oven temperature to 185°C fan/205°C/gas mark 4½ and bake for a further 15 minutes.
Serve the pies within 20 minutes of taking them out of the oven so that the cheese oozes and pulls into strings when the pies are cut open. Enjoy with a few steamed green beans and a little spiced tomato chutney on the side.
