Place a large pot filled with water on medium heat for cooking the pasta.
When the water comes to a boil, add plenty of salt along with the pasta, and give it a stir.
Cook the pasta a couple of minutes less than stated in the packaging, it will carry on cooking in the sauce while baking.
Preheat the fan oven to 200° C (390° F). Start your cheese sauce while the pasta is cooking.
Have a saucepan placed on medium heat to start your cheese sauce.
Add the butter to the saucepan, let it melt, and stir in the flour. Mix well using a wooden spatula or a whisk and cook for two minutes stirring all the time.
Whisk in a little of the warm milk at a time stirring continuously until you have a smooth, velvety sauce.
Cook on low heat for a few minutes stirring all the time until the sauce has thickened and the flour taste has disappeared.
Remove the pan from the heat and whisk in the salt, freshly ground black pepper, mustard powder, and stilton cheese.
Add the grated smoked gouda and cheddar cheese to the sauce.
When the pasta is cooked, drain it and add it to the pot with the cheese sauce, and give them a good stir.
Transfer the macaroni cheese into a baking dish, sprinkle on the panko, and bake it for 10-15 minutes, until the cheese has melted and the top is slightly browned.
Prepare the crispy bacon bits while baking the macaroni cheese.
Remove the macaroni cheese from the oven, and garnish it with crispy bacon bits, and chopped parsley.