1: Preheat the oven to 200°C/Fan 180°C/Gas 6 and place a large baking tray inside to heat up.
2: Lay a large piece of baking paper on your work surface and dust with a little flour. Place the pastry on the paper and roll it out to a 34cm circle. Leaving a 3cm margin around the edge (this will form a rim), prick the pastry well with a fork.
3: Mix the ricotta with the lemon zest and half the thyme leaves and season with a little salt and pepper.
4: Spread the onion chutney over the pastry base and then spoon on the ricotta mixture, spreading it in an even layer.
5: Distribute the beetroot slices evenly over the ricotta, overlapping them slightly, and season with a little salt and pepper. Arrange the goat’s cheese slices on top of the beetroot and scatter the hazelnuts evenly over the top.
6: Brush the pastry margin with beaten egg. Sprinkle over the remaining thyme leaves and then start to fold the pastry margin up over the edge of the filling, pressing each fold firmly until all the edges are folded inwards to form a rim. Brush the top of the folded pastry edges liberally with the remaining beaten egg.
7: Slide a flat baking tray under the baking paper and galette. Take the hot tray from the oven and carefully slide the galette off its tray and onto the hot tray.
8: Place the galette on a high shelf in the oven and cook for 35–40 minutes or until the pastry is a deep golden brown.
9: Remove the galette from the oven and leave it to sit for a few minutes. Drizzle a little extra virgin olive oil over the surface and cut the galette into thick wedges. Serve with a leafy salad on the side.