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Onion Potato Tart



  • ½ c/115g butter cold and cubed
  • 1 ½ c/245g all-purpose flour
  • ¼ tsp salt
  • ½ tsp ground pepper
  • ¼ c/60ml cream
  • ¼ c/60ml water


  • 2 tbsp/30g butter
  • 2 large onions/1 kg slice in ¼” thick semi-circles
  • 10 oz/300g small creamer potatoes cut in ¼” thick rounds
  • 4 tbsp/60ml crème fraiche
  • 1 tbsp/4g fresh thyme
  • ½ tsp salt


  • 1 egg
  • 1 tbsp/15ml water


For the pastry:

  • Combine flour, butter, salt, and pepper in a food processor. Pulse into coarse crumbles.
  • Add cream and water. Pulse until a dough forms and pulls away from the walls of the food processor.
  • Form into a flat disc, cover with plastic wrap, and chill in the fridge for at least 30 minutes.
  • Steam potatoes until just starting to tenderize – a sharp knife can be inserted. Set aside to cool.
  • Melt 1 tbsp butter in a pan on medium-high. Sauté onions until caramelized, stirring frequently, about 10-15 minutes depending on size of pan (it is a lot of onions).
  • Add crème fraiche, thyme, and salt to onions, tossing to combine. Set aside.
  • Preheat oven to 375F.
  • Roll out dough on a lightly flour surface. Roll to ¼” thick and about 18” around.
  • Assemble on a lined baking sheet: Place dough on sheet. Place potato rounds in a 9” circle on the center of the dough disc. Reserve 3-4 rounds for the top of the galette (optional).
  • Spoon the onion mixture on top of the potatoes, spreading evenly.
  • Fold the bare edges of the dough over the filling, giving the galette five or six edges.
  • Place the remaining potato slices in any desired pattern on top of the onion mix if desired.
  • Whisk water and egg together. Use a pastry brush to glaze the exterior of the dough and drizzle the remaining egg on the filling.
  • Bake for 35-45 minutes until the crust is golden and the filling is bubbling slightly.
  • Allow to cool for 10-15 minutes before serving. Also does well at room temperature.