Heat the oven to 180C/160C fan/gas 4 and line a baking tray with parchment. Put the caster sugar and 3 tbsp water in a small saucepan, and add the lemon zest. Bring to a simmer, bubble for a minute until the sugar has dissolved, then set aside to cool a little.

To make the frangipane, beat the butter and sugar together for a few minutes with an electric whisk. Add the ground almonds, flour, almond extract and egg, and beat for another minute until well combined.

Lay the slices of bread on the tray, then brush the syrup over each slice until it’s used up. Divide the frangipane between the slices of brioche and spread right to the edges. Put a handful of blueberries in the centre of each piece, then press as many flaked almonds around the edge of each piece as you can make stick.

Bake for 25-30 mins until the frangipane is golden brown. Cool for at least 10 mins before eating, then serve with a spoonful of crème fraîche, if you like.