Melt the butter in a saucepan over a medium heat until it starts to foam. Continue to cook for 4-5 mins until small bubbles start to appear – the butter should be golden brown and smell nutty. Remove from the heat and set aside to cool slightly.

Mix the icing sugar, almonds and plain flour in a large bowl. Gently stir in the egg whites, then gradually mix in the butter until smooth. Cover and leave to rest in the fridge for 1 hr.

Heat the oven to 200C/180C fan/gas 6. Lightly butter a 12-rectangle silicon baking tray and place on a flat baking tray. Carefully spoon the batter into the moulds, then use a flat knife to scrape any excess batter off the top. Sprinkle over the flaked almonds then bake for 16-18 mins until firm to the touch and golden.

Leave to cool for 10 mins before carefully turning out onto a wire rack to cool completely. Sieve over a little icing sugar to serve. Will keep in an airtight container for up to three days.