Roast the cauliflower. Heat oven to 425°F (220°C). Arrange the cauliflower florets in an even layer on a large baking sheet. Drizzle evenly with the olive oil, then sprinkle the smoked paprika, garlic powder, and a generous pinch of salt and pepper evenly over the cauliflower. Toss briefly to combine. Spread the cauliflower out in an even layer and bake for 25 to 30 minutes until lightly toasted around the edges. Remove baking sheet from oven and set aside, leaving the oven on.

Toast the breadcrumbs. Meanwhile, as the cauliflower is roasting, toast the Panko by cooking it in a large stockpot over medium-high heat, stirring frequently, until it turns golden brown (about 3-5 minutes). Transfer the breadcrumbs to a separate bowl, and briefly wipe down the stockpot so that it is clean.

Cook the pasta. Fill the same stockpot with water and bring it to a boil. Generously salt the water, add the pasta, then cook until it just reaches al dente. (Try to avoid overcooking the pasta since it will cook slightly more in the oven.) Drain pasta, return it to the stockpot, and set aside.

Make the cheese sauce. Meanwhile, as the pasta is being prepared, melt the remaining 3 tablespoons butter in a medium saucepan over medium heat. Add the garlic and cook for 1 minute, stirring occasionally. Add the flour and whisk to combine until the mixture is smooth. Gradually add the milk and whisk until combined and smooth. Continue cooking, stirring occasionally, until the mixture has thickened and almost reaches a simmer. Add in the cheeses plus a few twists of freshly-cracked black pepper and stir to combine. Continue cooking for 2 to 3 more minutes, stirring occasionally, until the cheese has completely melted and the sauce is smooth.

Combine and bake. Pour the sauce into the stockpot with the cooked pasta, add the roasted cauliflower and toss the mixture gently until combined. Transfer the mixture to a 9 x 13-inch baking dish, spread it out in an even layer and sprinkle the toasted breadcrumbs evenly on top. Bake uncovered for 5 minutes.

Serve. Remove from the oven and sprinkle with your desired garnish. Serve immediately while it’s hot and melty…and enjoy!