01 - Preheat oven to 375°F. Grease a 9x13 inch baking dish with butter or cooking spray.
02 - Bring a large pot of salted water to boil. Add macaroni and cook for 6 minutes. Add broccoli and continue cooking for 2 more minutes until pasta is al dente and broccoli is bright green. Drain thoroughly.
03 - In a large saucepan, melt 4 tbsp butter over medium heat. Whisk in flour and cook for 2 minutes, stirring constantly to form a smooth roux.
04 - Gradually whisk in milk and heavy cream. Continue whisking until sauce thickens and bubbles, about 5 minutes. Remove from heat.
05 - Stir in sharp cheddar, Gruyère, Dijon mustard, garlic powder, onion powder, salt, and black pepper until completely melted and smooth.
06 - Add cooked macaroni and broccoli to the cheese sauce. Mix gently until evenly coated. Transfer mixture to the prepared baking dish.
07 - In a small bowl, combine panko breadcrumbs, grated Parmesan, and melted butter. Mix until evenly distributed.
08 - Sprinkle crumb mixture evenly over the macaroni and cheese. Bake for 20-25 minutes until bubbling and golden brown on top. Allow to rest for 10 minutes before serving.