Start by making the biscuit base. Melt the butter in a saucepan then remove from the heat. Put the biscuits in a plastic food bag, seal the bag, then crush them to fine crumbs with a rolling pin. Transfer the biscuit crumbs to the pan with the melted butter and mix thoroughly. Press the buttery crumbs into the base and slightly up the sides of a 25 cm fluted, loose-bottom tart tin. Chill in the fridge for 30 minutes, until firm.
Melt half the white chocolate in a heatproof bowl over a pan of gently simmering water (don’t allow the base of the bowl to touch the water), then set aside.
Place the cream cheese and double cream in a bowl. Beat with an electric whisk or by hand until the mixture forms thick, soft peaks, then add the melted white chocolate, maple syrup and vanilla extract. Stir until smooth.
Remove the biscuit base from the fridge and spoon the cream cheese mixture onto the base. Smooth the surface, arrange the blueberries and raspberries on top, then decorate the tart with white chocolate shavings (using the remaining white chocolate) and drizzle with honey.