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A puff pastry slice filled with lobster with cabbage on the side

Lobster thermidor en croûte

Published: February 16, 2022 at 4:26 pm
  • Preparation and cooking time
    • Total time
    • + chilling
  • Easy
  • Serves 6

We've put a spin on classic salmon en croûte with a luxurious lobster thermidor filling. Serve this as a centrepiece on Christmas Eve with buttered cabbage


Make this impressive lobster thermidor en croûte, then check out our classic lobster thermidor and salmon en croute plus more Christmas Eve recipes.

Recipe tip: Buy whole cooked, frozen lobster from supermarkets during the Christmas period for a fraction of the live cost. This clever recipe makes two lobsters feed six, so it isn’t as expensive as it sounds, and makes for a showstopping centrepiece. There’s no need to carefully pick the meat either – it will get chopped and stirred into the sauce, and can be prepared a few days ahead of cooking. A light tap with a rolling pin will help crack the claws if you’re new to preparing them. Chill for up to a day before cooking to get ahead.


  • 50g unsalted butter, plus 1 tbsp
  • 50g plain flour, plus extra for dusting
  • 400ml whole milk
  • 1 bay leaf
  • finely chopped to make 1 tbsp tarragon
  • 65g gruyère, finely grated
  • 1 tbsp Dijon mustard
  • 2 leeks, sliced
  • 250ml dry white wine
  • 2 cooked lobsters, (defrosted if frozen), picked of all meat and chopped into chunks
  • 2 tsp brandy
  • 500g baby spinach
  • 500g block ready-made puff pastry
  • 1 egg, beaten
  • roast potatoes and buttered Savoy cabbage, to serve


  • STEP 1

    Melt 50g of butter in a pan over a medium heat, then sprinkle over the flour and stir vigorously until you have a smooth paste. Add the milk, a splash at a time, stirring continuously until you have a smooth white sauce. Add the bay, tarragon, gruyère and mustard, and cook for 2-3 minutes or until thickened. Remove from the heat.

  • STEP 2

    In a separate pan, heat the tbsp of butter and fry the leeks for 15 minutes until very soft – add a splash of water during cooking to stop them catching, if needed. Add the wine and simmer until evaporated. Stir into the white sauce along with the lobster meat and brandy. Cover and chill for 3 hours, or overnight, until set solid.

  • STEP 3

    Steam the spinach until wilted, then cool until you can handle it. Tip into a clean tea towel, wrap up and squeeze as much water as possible from the spinach.

  • STEP 4

    Cut off a third of the pastry and roll out on a well-floured worksurface into a 20cm x 30cm rectangle. Transfer to a heavy baking tray lined with baking paper. Arrange the spinach over the pastry rectangle, leaving a 4cm border around the edge, then spoon the lobster filling down the middle of the spinach.

  • STEP 5

    Roll out the remaining pastry as before into a 40cm x 30cm rectangle. Brush some of the beaten egg around the exposed pastry edges of the filled rectangle, then lay the larger rectangle on top. Crimp the edges with a fork or your fingers to enclose the filling and seal. Trim the excess and use the off-cuts to decorate the top, if you like. Brush the pastry all over with most of the remaining beaten egg, cut a large steam hole in the top and chill for 30 minutes.

  • STEP 6

    Heat the oven to 220C/fan 200C/gas 7. Glaze the pastry with any remaining beaten egg and bake for 45-50 minutes or until golden, puffed, crisp-based (lift a corner to check) and piping hot throughout. Leave to rest for 10 minutes before carving.

Find more impressive lobster recipes


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