Before starting this Langues de Chat Biscuits recipe, make sure you have organised all the necessary ingredients.
In a mixing bowl, place the soft butter and castor sugar.
Beat vigorously with a whisk until pale and fluffy.
Add the sifted flour, egg whites...
...and a few drops of vanilla extract.
Combine with a spatula until homogeneous.
Transfer the preparation into a piping bag fitted with a polycarbonate plain nozzle (diameter 10mm).
Slightly grease a langues de chat mould with an oil spray (recommended for an easy release).
Pipe the preparation in the mould cavities. Fill all the way up.
Preheat the oven to 180°C (gas 4) and bake for approximately 10 minutes.
After a few minutes, the preparation should spread out a bit and the biscuits should be golden.
After 10 or 12 minutes, the biscuits are cooked. Remove from the oven.
Set aside to cool before releasing from the mould. The biscuits should come off easily. Important: This tinplate mould should not be put in the dishwasher or washed with water, but simply with a cloth instead.
Alternatively, if you are not using a langue de chat mould, you can pipe the preparation into strips (7 or 8cm) on a non-stick baking sheet, or on a Silpat silicone baking mat (as shown on the photo).
Preheat the oven to 180°C (gas 4) and bake for about 10 minutes. The preparation will spread out a bit while cooking and the edges will be golden in minutes.
When cooked, let cool before removing from the sheet. To preserve these biscuits, place them in an airtight container.