Taken from My Wild Atlantic Kitchen: Recipes and Recollections, by Maura O’Connell Foley
Makes 8 pastries
Prawn and spinach filling
Noilly Prat sauce filling
Pastry
Mousseline sauce
To serve
Preheat the oven to fan 200°C with a baking tray inside.
To make the prawn and spinach filling, bring the water to the boil with a pinch of salt in a wide saucepan. Add the prawns and turn off the heat immediately, leaving them to rest in the poaching liquid for two minutes or until just cooked. Transfer the prawns to a plate, cover and allow to cool. Reserve the poaching liquid for the Noilly Prat sauce.
Bring another saucepan of water with a pinch of salt to the boil, plunge in the spinach and stir for 30 seconds or until bright green. Drain and refresh in ice-cold water. Once cold, squeeze out the liquid from the spinach and toss in the melted butter with sea salt and cracked black pepper to taste.
To make the Noilly Prat sauce filling, return the prawn poaching liquid to the heat and reduce by two-thirds. In another saucepan, melt the butter over a low heat, then stir in the flour for 3-4 minutes to make a roux. Gradually stir in the reduced poaching liquid, cream and Noilly Prat to a smooth sauce. Season with sea salt and cracked black pepper to taste.
To prepare the pastries, have the melted butter and filo pastry at hand, keeping the pastry well covered in cling film. Further cover with a damp tea towel to prevent it from crumbling, but do not allow the tea towel to touch the pastry directly.
Lay out one sheet of filo and brush with butter, ensuring the sheet is entirely coated with butter right out to the edges.
Lay a second sheet carefully on top for a double layer and brush with butter. Using a sharp knife, cut the pastry lengthways down the centre and then again across to quarter the pastry, which will give you two good-sized parcels.
Take a heaped spoonful of spinach and place in the centre of the pastry, with a heaped teaspoon of the Noilly Prat sauce on top. Add 3-4 prawns followed by another teaspoon of the Noilly Prat sauce. Fold the long part first from the bottom over the filling.
Brush with butter again, then fold down from the top part. Butter, then fold under the outer sides and butter. Repeat with the remaining filo and filling to make eight parcels in total.
Place the folded filo parcels on the preheated oven tray and bake for about 12-15 minutes or until golden all over. Baking time will depend on your oven.
To make the mousseline sauce, make the hollandaise egg base by melting the butter in a small saucepan until it starts to boil then remove from the heat.
Meanwhile, place the water and yolks in a food processor and blend until pale and fluffy. Very gradually start to pour the hot foaming butter via the funnel into the processor, keeping the motor running, until it starts to emulsify. You can then add the remaining butter more swiftly while still hot. Add the lemon juice via the funnel and blend.
Transfer the mixture into the saucepan used to melt the butter and fold in the freshly whipped cream.
Serve the pastries with the mousseline sauce and a sprig of fennel to garnish.