01 -
Preheat the oven to 425°F (220°C) and move the wire rack one shelf above the center. Wash cauliflower, cut off the leaves, and divide into florets. Place the florets on a large baking sheet and pat dry with paper towels. Toss the florets with olive oil and season with salt and pepper. Bake for 20 minutes or until browned and softened but not very soft. Take out of the oven and transfer to a 9x13-inch (23x33cm) baking dish.
02 -
Melt the butter in a small pot, stir in Panko until evenly coated in butter. Take the pot off the heat and stir in parmesan. Set aside.
03 -
Dice the shallot, finely chop garlic, juice the lemon, and grate the Gruyere on the large holes of a box grater. Melt the butter in a large frying pan, add the shallots, and cook over low heat for about 2 minutes or until softened. Add garlic, thyme, paprika, and flour. Cook for a minute, stirring. Add milk, cream, Dijon, and cook for 2-3 minutes, stirring, until slightly thickened. Add 1/2 of the Gruyere cheese and cook until it's melted. Take the pan off the heat, season the sauce with lemon juice, salt, and pepper.
04 -
Add the sauce to the cauliflower. Stir until evenly coated. Top with the remaining 1/2 of Gruyere, then sprinkle breadcrumb parmesan topping over the sauce. Bake for 25 minutes or until the topping is golden and the casserole is hot and bubbly.