Preheat oven to 180°C. Line a large oven tray with baking paper.

Place grape tomatoes, garlic and 1 tablespoon of the oil in a bowl; season, then toss gently to coat. Place on lined tray in a single layer; roast for 30 minutes or until tomatoes are blistered. Leave to cool.

Meanwhile, whisk eggs and half the cream cheese in a bowl until combined and smooth.

Place one sheet of pastry on a large sheet of baking paper. Cut the second pastry sheet into three strips. Join one strip to the left side of the whole pastry sheet and another strip to the top side. Use remaining strip to patch the gap in the corner to create one large pastry sheet; discard remaining pastry.

Turn pastry sheet, on paper, into a 3.5cm deep, 24cm round loose-based fluted tart tin. Peel away paper; press pastry gently into tin, pressing edge to line up side. Prick pastry base with a fork; freeze for 10 minutes.

Line pastry with baking paper; fill with dried beans or rice. Place on an oven tray. Bake for 10 minutes on the lowest oven shelf. Remove paper and beans; brush with 2 tablespoons egg mixture. Bake for a further 15 minutes or until pastry is golden. Leave to cool completely. Reduce oven temperature to 160°C.

Meanwhile, brush corn with another 1 tablespoon of the oil. Grill on a hot grill pan (or plate), turning occasionally, for 10 minutes or until corn is cooked and grill marks appear. Brush truss tomatoes with remaining oil; cook for 1 minute or until skins start to burst.

When corn is cool enough to handle, cut kernels from cobs in large sections. Add corn, grape tomatoes and half the basil to egg mixture; season. Pour egg mixture into case; bake for 50 minutes or until filling is set and tart shell golden.

Process remaining cream cheese, basil, chives, juice and 1 tablespoon water until smooth. Serve tart topped with truss tomatoes and herbed cream cheese.