For 50 macarons
Preparing the filling
Put the gelatin sheet in cold water. Heat the glucose syrup with the sugar in a pan until caramelised and golden. Remove from the heat and add the double cream. Let it cool down, stirring constantly and keeping an eye on the temperature. When the caramel gets to 40 °C, stir in the drained gelatin. Mix well and add the butter. Stir the mixture for several minutes. Coarsely chop the walnuts and add them to the caramel. Set aside.
Blend the walnut powder and icing sugar together to obtain a very fine powder. Break the eggs, separating the yolks and the egg white. Weigh out 150 g of egg whites. Stir half of the egg whites (75 g) into the walnut and sugar mixture. Set aside. Heat the water and sugar in a pan to make a syrup. Check the temperature regularly: when it is almost at 118 °C, pour the remaining 75 g of egg white into a mixing bowl and gently beat. When the syrup reaches 118 °C, slowly pour it into the mixing bowl and stir. The mixture should become thick and shiny. Fold it into the mixture you set aside earlier.
Pre-heat the oven to 150 °C (Gas 2). Fill a piping bag with a plain 10 mm nozzle. Pipe circles of about 3 cm in diameter on a baking sheet lined with baking parchment.
Leave to rest 30 minutes at room temperature until a skin has formed (the batter should no longer be sticky when touched lightly). Bake in the oven for about 8 minutes. Open the oven door and continue baking for another 4 minutes without browning the tops.
Spread a knob of caramel on one half and sandwich with a second half. Do the same for each macaroon. Leave to rest in the fridge for 24 hours before eating.
Author and photograph: Philippe Barret