Preheat the oven to 200°C (180°C fan). Toss the cauliflower florets with olive oil, fenugreek, paprika, salt, and pepper. Roast for 20–25 minutes until golden and slightly crisp.
In a saucepan, melt the butter over medium heat. Stir in the flour to make a roux, then slowly whisk in the milk until smooth and thickened.
Remove from the heat and stir in the Cheddar, Gruyère, and Parmesan until melted and smooth. Season to taste, reserving a little cheese to sprinkle on top later.
Place the roasted cauliflower in a baking or stoneware dish. Pour over the cheese sauce, then sprinkle the remaining cheese on top.
Return to the oven for 20 minutes until bubbling and golden.
Serve as a rich side dish or a comforting vegetarian main.
