Lobster Thermidor is a celebrated dish of French culinary heritage, born in the late 19th century and named after a play performed during the French Revolution’s Thermidorian month. The original dish features lobster meat returned to its shell and gratinéed under a rich, creamy mustard and wine sauce, often enhanced with cheese and fine herbs. A true showstopper of classical French technique, it brings together elements of béchamel, reduction sauces, deglazing with wine or brandy, and gratinée finishes under the grill.
But the Thermidor of today is evolving. As more people seek vegetarian alternatives for reasons of sustainability, health, or ethics, chefs and home cooks alike are turning to vegetables as the centrepiece of classic dishes. The goal is not to mimic meat but to honour the sauce and method while letting the vegetable’s character shine.
This Roast Cauliflower Thermidor does exactly that. Cauliflower, with its dense, meaty texture and mild sweetness, makes the perfect carrier for a sauce as rich and nuanced as Thermidor. It holds up beautifully to roasting and gratinéeing and pairs harmoniously with mustard, wine, and cheese. As a member of the brassica family, cauliflower brings a subtle earthiness that balances the decadence of the sauce. At the heart of this dish lies a velvety, cheesy sauce—rich with Gruyère and Parmesan, with just enough mustard and wine to cut through the decadence.
Here’s how to bring this elegant dish to life.
Roast Cauliflower Thermidor
Serves 4
Ingredients
Cauliflower
- 1 large cauliflower (about 1kg), whole
- 2 tbsp olive oil
- Salt and freshly ground black pepper
Thermidor Sauce
- 25g butter
- 25g plain flour
- 3 banana shallots, finely chopped
- 1 garlic clove, minced
- 1 bay leaf
- 100ml white wine
- 250ml chicken or vegetable stock
- 250ml whole milk
- 50ml double cream
- 1 tsp English mustard
- ½ lemon, juiced
- A pinch of fine herbes (chervil, chives, tarragon)
- 10g finely grated Parmesan
- 20g Gruyère, grated
- Tabasco, to taste (about 5 dashes)
Method
1. Prepare the Cauliflower
- Bring a large pot of salted water to the boil.
- Add the whole cauliflower and blanch for 10 minutes until just tender.
- Remove and let it steam dry completely. Once cool enough to handle, cut it in half.
- Drizzle generously with olive oil, season with salt and pepper, and roast in a preheated oven at 200°C (390°F) for 20 minutes until golden and lightly crisped.
2. Make the Thermidor Sauce
- In a saucepan, melt the butter, then stir in the flour to make a light roux.
- Add the shallots and garlic, and sweat gently for 5 minutes until soft.
- Stir in the mustard, then deglaze the pan with white wine, scraping up any bits from the bottom. Let it reduce by half.
- Add the stock, bay leaf, and milk, stirring continuously as it simmers and thickens slightly.
- Stir in the cream, Parmesan, and Gruyère. Let it bubble until smooth and velvety.
- Add lemon juice, herbs, and Tabasco to taste. Remove the bay leaf. Season with salt and pepper. Set aside.
3. Bake the Cauliflower with Sauce
- Place the roasted cauliflower halves cut-side up in a baking dish.
- Spoon the warm Thermidor sauce over the cauliflower.
- Return to the oven and bake for 15 minutes at 190°C (375°F).
- Finish under the grill for 2–3 minutes until the top is golden and bubbling.
- Serve hot, optionally garnished with extra herbs and a crisp green salad on the side.
