Preheat the oven to Gas Mark 6/200°C/400°F. Use the pastry to line a 20 cm (8-inch) fluted deep flan tin. Trim the edges, line the base with greaseproof paper and fill with baking beans. Bake for 20 minutes, removing the beans for the final 5 minutes.
Spread the pesto sauce over the base and scatter over a third of the Cheddar. Beat the eggs, crème fraîche, chives and seasoning together, and stir in the remaining cheese. Pour into the pastry case and bake for 20 minutes or until the filling is beginning to set.
Arrange the sliced tomatoes on top of the quiche, overlapping them slightly. Brush with the oil and bake for a further 30 minutes.
Serve warm or cold.