Mini eclair fingers with apple purée and hazelnut butter

Preheat oven to 180°C. Sift flour with a pinch of salt onto a piece of kitchen paper. Put water and butter in a roomy saucepan and heat gently until butter melts. Bring to a rolling boil, remove pan from the heat, shoot in the flour in one go and beat vigorously until the mixture is amalgamated and comes away from the sides of the pan. As soon as it does that, stop beating. Cool.

Lightly beat eggs with a large pinch of salt. When the paste is cool, add eggs a little at a time, beating well after each addition, until the mixture is smooth and glossy (easily done with a hand-held electric beater).

Line a baking sheet with baking paper and splash with a few beads of water. Fit a large piping bag with a 1cm plain piping nozzle and fill with choux paste. Pipe shapes 5-6cm long onto baking sheet. Transfer to the top-third of the oven then immediately increase heat to 200°C. Bake until crisp and brown (18-20 minutes) then slide off baking sheet onto a cooling rack. Poke a small hole in each éclair with a skewer and leave to cool. (If the éclairs seem a little gooey in the centre, return them to the turned-off oven for 5 minutes to dry out.)

Put apples in a sturdy saucepan with the water. Cover with a lid and cook gently for about 15 minutes or until the apples turn to fluff. Beat with a wooden spoon to soften the purée. Push apples through a coarse sieve and discard skin, cores and pips. Return apple purée to a clean pan with sugar and set over a medium heat. Cook for about 10 minutes, stirring frequently, until it has reduced and is thick enough to stick to the wooden spoon. Cool.

Either pipe the apple purée into the éclairs with a piping bag and small nozzle (enlarge the hole you made when cooling éclairs in step 3), or split the éclairs enough to smear in the purée with a small knife. Blend softened butter and icing sugar together in a bowl then mix in 2 tbsp chopped hazelnuts and the lemon zest. Spread over top of éclairs, then press gently into chopped pistachios or remaining hazelnuts. Once filled and decorated, serve within 1 hour.