Preheat your oven to 350°F (175°C). While it’s warming up, thoroughly rinse the broccoli florets. Trim any woody stems. After that, steam or blanch them in boiling water for about 3 minutes, until slightly tender. You want to keep their vibrant color. A quick plunge in ice water will halt the cooking process.

In a medium saucepan, melt 2 tablespoons of butter over medium heat. Stir in the flour and cook for about 1 minute to create a roux. Gradually whisk in the warmed milk, ensuring no lumps form. Continue whisking until the sauce thickens.

Add in 1 ½ cups of cheddar cheese, stirring until melted and combined. Season with salt, smoked paprika, and black pepper. This sauce is your golden elixir.

In a large bowl, combine the steamed broccoli with the cheese sauce. Gently fold until the broccoli is well-coated. Pour the mixture into a greased 9x13 baking dish.

Melt the remaining tablespoon of butter and mix it with panko breadcrumbs. Sprinkle the buttery breadcrumbs over the casserole. Top with the remaining cheddar cheese and the grated Parmesan. This crunchy layer is key to texture.

Slide the casserole into the oven for about 30 minutes, or until the top is golden brown and bubbly. Let it rest for a few minutes before digging in.