1. COMBINE the flour, sugar and butter in a food processor and process just until mixture resembles breadcrumbs. Add the egg and process briefly until mixture begins to form lumps. Remove and gently knead to form a soft dough. Shape into a disc, wrap in plastic wrap and refrigerate for at least 30 minutes. Roll out on a lightly floured surface using a lightly floured rolling pin and line a 35cm x 12cm rectangular fluted tart pan with a removable base. Chill for 30 minutes then prick well with a fork.
2. BAKE in a hot oven 200oC for 10 minutes, reduce the heat to 180oC and then bake for a further 5 minutes or until golden. Cool.
3. COMBINE the extra ½ cup sugar and custard powder in a saucepan, stir in the milk and vanilla then whisk over a medium heat until custard boils and thickens. Cover and chill until firm. Beat the cold custard until smooth. Gradually add the PHILLY and melted chocolate and beat until smooth. Chill.
4. COMBINE the rhubarb, orange and extra sugar in a shallow pan and cook gently for 10 minutes or until just tender. Cool.
5. SPREAD the custard into the prepared base, top with the rhubarb and drizzle over any juice. Serve immediately.