Bring a large pot of salted water to the boil and cook the pasta until just al dente (1 – 2 mins less than packet instructions). Drain and set aside.
Heat olive oil in a large frying pan over medium heat and fry the sausages for 8 minutes, turning every minute, until cooked through and golden brown.
Remove and set aside.
In the same pan, add the sliced leeks and cook gently for 3 minutes.
Add mushrooms and cook for 4 minutes until golden. Stir in the garlic and cook for a further minute.
Make the creamy sauce:
Stir the flour into the vegetables and cook for 1 minute.
Gradually pour in the stock, stirring constantly until smooth and slightly thickened. Add the cream and Dijon mustard, and simmer for 2 – 3 minutes.
Season with salt and black pepper.
Assemble
Add the cooked sausages and drained pasta to the pan, tossing to coat in the creamy sauce. Transfer to a large ovenproof dish. Sprinkle with 100g of grated Dromona. Bake in a preheated oven at 200°C (180°C fan) / Gas 6 for 20 – 25 minutes, until golden and bubbling.
Cook peas according to packet instructions.
Serve the pasta bake piping hot, accompanied by a generous spoonful of peas on the side.
Fresh Pasta Option: If using fresh pasta, reduce the pasta cooking time to just 1 – 2 minutes (you only need to blanch it, as it will continue cooking in the oven). Use approximately 700g of fresh pasta instead of 500g of dried pasta.