Tip the flour and butter into a food processor and blitz together until you have a crumb. Add the first egg and blitz. Add the second egg along with the basil and blitz again. Add water if needed to help the pastry blend - it should then come together as a soft dough.
Divide the pastry so you have roughly two-thirds in one ball and one-third in the other. Wrap the pastry balls in clingfilm and place in the fridge to firm up while you make the filling.
Using a mandolin, sharp knife or vegetable peeler, slice all the vegetables as thinly as you can. This won't just help to cook the vegetables evenly, but faster too. Put each set of vegetable slices in separate microwave safe bowls.
Season the vegetables with salt and pepper then drizzle with 1tbsp olive oil per bowl. Microwave on a high for 3-5 minutes per bowl until everything is cooked through. This will use at least 10% less energy compared to cooking it in the oven. Press out at much liquid as possible from each of the vegetable bowls - this will help to ensure your pie isn't soggy. You can save the liquid for stock, if you wish.
Retrieve the larger ball of pastry and place it on a floured surface.
Roll out flat so that it's at least a couple of inches wider than your pie tin all the way round. Carefully transfer your pastry to the bottom the pie dish, press to cover the base evenly. If any holes appear, repair them with a little extra pastry. Do not trim the overhanging pastry yet.
Use half the courgette to form your first layer, followed by half of the mushroom and then half of the aubergine, aiming each time for evenly spread layers. Top with half of the passata.
Repeat with another layer of the courgette, mushrooms and aubergine. Top with the remaining passata and smooth over the top.
Switch your oven on to 200C/390F (180C/355F fan) and place a baking tray on the middle shelf.
Roll the remaining pastry out until you have a round slightly larger than the dish and lay it on the top of the pie. Press a fork all the way round to seal the edges, then cut away the spare with a sharp knife.
You can use some of the pastry offcuts to make whatever decorations you fancy. I went with some leaves to highlight the basil in the crust. Affix the leaves with a little egg wash and then brush the egg wash all over the pastry. Finally cut a few slits through to the filling for steam to escape.
Place your pie on top of the hot baking tray in the oven for 35 minutes, then turn the oven off and let the pie continue to cook for a further 5 minutes. The oven will retain a lot of heat, meaning you can finish off the pie without using any more energy.