Name: Lobster thermidor en croûte
Total time: 2 h
Yield: Serves 6
Ingredients: 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

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

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

Method

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.