• 1 tablespoon butter
  • 800 grams sweet potatoes, peeled and sliced into 2mm rounds
  • 1 white onion, thinly sliced
  • 2 garlic cloves, finely chopped
  • 100 milliliters whole milk
  • 300 milliliters Heavy cream
  • 80 grams cheddar, grated
  • 100 grams parmesan cheese, grated
  • Sea salt and ground black pepper, to taste


  1. Preheat the oven to 180. Grease a ovenproof gratin dish with the butter. Begin by layering the potatoes in rows in the dish, ensuring that they overlap slightly. After your first layer, add an even layer of onions, followed by the garlic, salt and a good grating of the parmesan. Repeat with the potatoes and remaining mix until everything is done, finishing with the potatoes. In a large jug, mix together the milk and cream. Season with salt and pepper. Pour the mix evenly on top of the potatoes, then gently press the potatoes down with a flat spatula so they are covered in the cream mixture. Sprinkle the cheddar and the remaining parmesan cheese on top of the mix and cover with foil. Place in the oven and bake for 15 minutes until the potatoes are almost tender. Remove the foil and bake for another 15 minutes until golden and bubbly.