01 - Preheat the oven to 400°F. Line a baking tray with parchment paper.
02 - Spread the butternut squash cubes on the prepared tray. Drizzle with 1 tsp olive oil and season with salt and black pepper. Roast for 25 minutes or until tender and lightly browned.
03 - While the squash roasts, cook the macaroni in salted boiling water according to package instructions until al dente. Drain and set aside.
04 - In a large saucepan, melt the butter over medium heat. Add the chopped onion and minced garlic; cook until softened, about 3 to 4 minutes.
05 - Stir in the flour and cook for 1 minute, then gradually whisk in the milk. Continue cooking and stirring until the sauce thickens, approximately 5 minutes.
06 - Add the roasted butternut squash to the sauce and puree using an immersion blender or transfer to a blender until smooth.
07 - Stir in the cheddar cheese, Parmesan, ground nutmeg, mustard powder, salt, and black pepper. Remove from heat once the cheese has melted and the sauce is smooth.
08 - Mix the cheese sauce with the drained macaroni. Transfer the mixture into a lightly greased baking dish.
09 - In a small bowl, combine panko breadcrumbs with 2 tsp olive oil and 0.7 oz grated Parmesan. Sprinkle evenly over the pasta.
10 - Bake for 15 minutes or until the top is golden and bubbling. Allow to rest for 5 minutes before serving.