Method

• 1.
  Preheat oven to 180°C. Grease and line base and sides of a 22cm springform pan.
• 2.
  Heat oil in a frypan over medium-low heat. Add onion, season, then cook for 8-10 minutes, stirring occasionally, until the onion has softened but not coloured.
• 3.
  Arrange a layer of potato around the sides of the pan with edges overlapping. Arrange 2 layers of potato over the base, brushing second layer with butter. Top with one-third each of the onion, cheese and chopped sage. Season, repeat layers twice, then finish with a layer of potato. Brush with butter, then loosely cover with foil.
• 4.
  Place the galette on a baking tray and bake for 45 minutes or until tender when pierced with a skewer. Remove the foil and continue to bake for a further 45 minutes or until brown. Rest galette in the pan on a wire rack for 10 minutes.
• 5.
  Meanwhile, melt the extra butter in a pan over medium heat. Add the extra sage leaves, then fry for 1-2 minutes until crisp. Drain on paper towel.
• 6.
  Garnish the galette with the crisp sage leaves, then slice into wedges and serve.