01 - Preheat oven to 400°F and grease a medium baking dish thoroughly.
02 - Bring a large pot of salted water to a boil. Cook macaroni according to package instructions until al dente. Drain and set aside.
03 - In a saucepan, melt 2 tablespoons butter over medium heat. Add flour and whisk for one minute to develop a roux.
04 - Gradually whisk in milk, stirring constantly until the mixture thickens, about 3 to 5 minutes.
05 - Incorporate cheddar, mozzarella, curry powder, curry paste if using, soy sauce, garlic powder, onion powder, and season with salt and pepper. Stir until the cheeses melt and sauce becomes smooth.
06 - Add drained macaroni to the sauce, mixing until thoroughly coated. Transfer this mixture into the prepared baking dish.
07 - Melt 3 tablespoons butter in a skillet. Add panko breadcrumbs and toast, stirring frequently, until golden. Stir in sesame seeds.
08 - Evenly sprinkle the toasted panko mixture over the mac and cheese. Bake for 20 to 25 minutes until bubbling and golden on top.
09 - Top with sliced spring onions and pickled ginger before serving, if desired.