01 - Preheat the oven to 400°F. Grease a medium baking dish if preparing the topping.
02 - Bring a large pot of salted water to a boil. Cook pasta according to package instructions until al dente. Drain and set aside.
03 - In a medium saucepan, combine butternut squash, onion, garlic, and vegetable broth. Bring to a boil, then reduce heat and simmer 12 to 15 minutes until squash is tender.
04 - Use an immersion blender or transfer to a blender to puree the mixture until smooth.
05 - Stir in milk and butter until fully melted and blended. Return sauce to low heat.
06 - Add cheddar and Parmesan cheeses, stirring until melted and smooth. Season with smoked paprika, nutmeg, salt, and pepper.
07 - Mix the cooked pasta and sauce thoroughly in a large bowl. Transfer to the prepared baking dish if using topping.
08 - Combine panko breadcrumbs with melted butter and sprinkle evenly over the pasta mixture.
09 - Bake for 12 to 15 minutes until the topping is golden and bubbly. Serve warm.