To make the pesto, combine all the ingredients together in a blender and blend until almost smooth, leaving texture in the sauce to make it interesting.
Preheat the oven to 160 degrees Celsius.
Brush the zucchinis, mushrooms and tomatoes lightly with the olive oil then roast for 20 minutes.
Turn the oven down to 150 degrees Celsius.
Spread the pesto over the base of the pastry shell, layer the vegetables on top, cover with foil and heat through in the oven for 20 minutes.