Cook the macaroni: Bring a large pot of salted water to a boil. Add the macaroni and cook according to the package instructions until al dente. Drain and set aside.
Prepare the cheese sauce: In a large saucepan, melt the butter over medium heat. Add the flour and whisk constantly for about 1 minute to form a roux. Gradually add the milk, whisking continuously to avoid lumps. Cook for about 5 minutes, or until the sauce thickens. Stir in the garlic powder and mixed spice.
Add the cheese: Remove the saucepan from heat and stir in the cheddar and parmesan cheeses until melted and smooth. Season with salt and pepper to taste.
Combine the pasta and sauce: Add the cooked macaroni to the cheese sauce, stirring to ensure all the pasta is well-coated.
Prepare the topping: In a small bowl, mix the bread crumbs with a bit of melted butter (optional for extra crispiness). Sprinkle the bread crumbs evenly over the mac and cheese.
Bake (optional): For a golden, crispy topping, transfer the mac and cheese to a baking dish, sprinkle the bread crumbs on top, and bake in a preheated oven at 180°C for about 10 minutes, or until the top is golden brown and crispy.
Garnish and serve: Sprinkle with fresh parsley or thyme leaves before serving. Enjoy your easy mac and cheese with bread crumbs and parsley!