2) Place the chopped bacon on a baking tray and cook in the oven until half cooked, about 10 mins. Drain off excess grease, reserve the bacon.
3) In a large pot of boiling, salted water, cook the elbow macaroni until al dente, about 8 to 10 mins. Strain, toss lightly in olive oil, reserve.
4) In a saucepan, on medium-high heat, saute the bacon with a light amount of olive oil. Add the onion and cook until translucent then add the garlic. Dust with flour, then whisk in milk, cream, nutmeg and mustard powder.
5) Bring to a simmer stirring constantly for several minutes. Whisk in 450g of the cheddar and 50g of the parmesan. Stir until all the cheese is melted. Adjust the seasoning with salt, pepper and lemon juice. Fold in the pasta, sage and parsley.
6) Place into the buttered baking dishes. Top with the remaining cheeses and place on baking tray and then into the oven. Bake until golden brown, about 20 to 25 mins.
7) Leave to cool for about 5 mins, garnish with parsley and sage leaves and serve.