Step-by-Step Instructions:
Preheat the oven to 375°F (190°C).
- Cook the cauliflower florets in boiling water for 5 minutes, then drain.
- In a saucepan, melt butter and whisk in flour to make a roux.
- Gradually add milk, stirring continuously, until the sauce thickens.
- Stir in half of the Gruyère and Parmesan cheeses, season with salt, pepper, and a pinch of nutmeg.
- Add the cauliflower to the sauce, mixing gently.
- Transfer to a baking dish and sprinkle with the remaining cheese.
- Bake for 20-25 minutes until the top is golden and bubbly.
