The night before you make the galette, wrap the butter and put it in the freezer.

Place a jug of cold water in the freezer for 30 mins before using in the pastry.

When you’re ready to make the pastry, put the plain flour, 20g of the grated parmesan and the sea salt in a large mixing bowl.

Take the butter out of the freezer and wrap one end in foil, then use this to hold it as you coarsely grate the butter into the flour mixture. Unwrap the last piece of butter and carefully grate that in as well.

Roughly mix everything, then add 5-6 tbsp ice cold water and mix swiftly with a cutlery knife to combine, then use your hands to bring it together into a dough and knead briefly. 6.Wrap and chill in the fridge for at least 1 hr. Will keep in the fridge for up to two days.

For the topping, heat the olive oil and butter together in a large, non-stick frying pan. Add the onions and a pinch of salt and fry over a low heat for 15 mins, stirring regularly until the onions are softened and sticky. Leave to cool for 15 mins.

Roll the pastry out between two pieces of baking parchment to a round, roughly 35cm. Peel off the top layer of parchment and grate over the remaining 15g parmesan. leaving a 4cm border. Top with the softened onions then sliced tomatoes, olives and capers. Fold in the edges of the pastry to slightly overlap the topping using the parchment to push the edges over the filling. Brush the edge with the beaten egg and grate over some extra parmesan around the edge. Use the parchment underneath to slide the galette onto a baking sheet. Chill for 30 mins.

Heat the oven to 240C/220C fan. Place a flat baking sheet in the oven for 20 mins to get really hot. Once chilled, slide the galette along with the parchment on to the hot baking sheet. Close the oven and immediately turn down to 200C/180C fan. Bake the galette for 30 mins until golden brown. Leave to sit for 5 mins.

Top with the anchovies, basil and an extra drizzle of olive oil.