Bring a large pot of salted water to a boil. Add the pasta and cook according to package instructions until al dente. Drain and set aside.
Set oven to broil.
Place broccoli in a microwave safe bowl, add 1 tbsp of water and cook for two minutes. Remove. Drain water and set aside.
In an 11-inch (28 cm) frying pan, heat butter over medium high heat. Remove one tablespoon of butter and add it to the panko breadcrumbs. Mix well and set aside.
In the pan, sprinkle the flour over the butter, whisking continuously, cooking for two minutes. Slowly drizzle in the milk, whisking continuously to avoid lumps.
Cook for three minutes or until sauce begins to thicken.
Remove from heat. Add in the cheeses, a cup at a time, stirring constantly. Add mustard, smoked paprika, salt and pepper and mix well. Add cooked pasta and broccoli and stir to combine.
Sprinkle panko breadcrumbs evenly over the top and place under the broiler for four to five minutes or until lightly browned.
Remove from oven and serve immediately.