Preheat the oven or air fryer to 180°C.
Slice the croissants into 1cm thick pieces.
In a bowl, whisk together the cream, egg, vanilla extract and date syrup or sugar.
Briefly dip some of the croissant slices into the custard mixture and arrange them in two ramekins or silicone baking dishes to cover the base.
Scatter over some of the blackberries and flaked almonds.
Repeat the layers with more soaked croissant slices, followed by more blackberries and almonds.
Finish with a final layer of croissant slices, then pour over any remaining custard mixture.
Sprinkle the remaining flaked almonds over the top and, if you like, add a light sprinkling of muscovado sugar for extra colour.
Bake for about 10–15 minutes in the oven, or 12–15 minutes in the air fryer, until the custard has set and the top is lightly golden.
Leave to cool for a few minutes before serving.
Serve warm with custard or vanilla ice cream, or chill and serve with a spoonful of Greek yoghurt.