Preheat oven to 425 degrees. Coat a large baking dish with nonstick spray and set aside.
Bring a large pot of water to a boil; add fusilli.
Cook pasta, stirring frequently. About a minute before it's done cooking, add the broccoli. When pasta is al dente, drain it and the broccoli in a colander.
Meanwhile, heat the milk in a microwave (or small pot) until warm, about a minute or two. Set aside.
Melt the butter in a large pan over medium heat, then add the garlic and cook until fragrant, about 30 seconds.
Add the flour, paprika, and cayenne to the butter and cook, stirring constantly, for a couple minutes.
Slowly add the milk, whisking to avoid lumps. Cook mixture until thickened (it should coat a spoon), then add the cheese and whisk until smooth. Remove from heat, then season generously with salt and pepper.
Stir pasta and broccoli into cheese sauce. Transfer to baking dish.
Combine panko, olive oil, and garlic in a small bowl. Season to taste with salt and pepper, then sprinkle over pasta.
Bake until hot and lightly browned on top, about 20 to 25 minutes.