Making the wholemeal pastry: place the flours, salt, pepper and Parmesan in the bowl of a food processor and process for about 30 seconds to combine.

Add butter and process for another 30 seconds, until the mixture has the consistency of coarse breadcrumbs. Add the milk, water and lemon juice, then pulse until the dough just start to come together in uneven clumps.

Tip the dough out onto a clean work surface and knead for a few seconds to bring it together into a ball. Wrap the ball loosely in plastic wrap, then press to flatten it into a disc. Refrigerate for an about 45 minutes (but it will keep in the fridge for up to 2 days).

Meanwhile, prepare the filling: heat the oil in a large frying pan and cook the onions and salt over medium low heat, stirring occasionally, for about 12 minutes, until soft and translucent. Add the garlic, thyme and cook for about 2 minutes, stirring regularly, then remove the pan from the heat and set aside to cool.

Combine the ricotta, chopped anchovies and lemon zest in a small bowl. Smoosh some of the anchovies into the ricotta with the back of a spoon and stir well to combine, then set aside.

Make the olive and caper topping by putting all the ingredients except the olive oil in a small bowl, then set aside. The oil will go later.

Remove the disc of dough from the fridge. It has been in the fridge for more than a few hours, leave it on the kitchen bench for about 10 minutes to soften a little. Lightly dust a large sheet of baking paper with flour, and lightly flour the bench too. The dough will be larger than the baking paper once rolled out.

With a small offset spatula or spoon, spread about two third of the ricotta mix in a thin layer all over the pastry circle and right up to the edges. Now scatter the onions all over the pastry, leaving a 4 - 5 cm clear border all around.

Then, spoon the olive and caper topping all around the perimeter of the onions, leaving the ricotta border clear, scatter the tomatoes, cut-side up, all over the tart, again leaving the border clear.

Finally, use a teaspoon to dollop small mounds of the remaining ricotta mixture all over the filling, the carefully draw the pastry border up and over the top, roughly pleating it as you go, and leaving the centre of the galette exposed.

Bake for about 40 minutes until the pastry is golden brown, then remove from the oven and set aside to cool for about 30 minutes.