Potato and Caramelized Onion Gratin

  • Preparation 30 MIN
    Cooking 50 MIN
  • Servings 12
Timing an elaborate meal is tricky, but we have a tasty cheat for mashed potatoes: Transform them into a gratin by spreading caramelized onions over them and topping with cheese. Prepare the day before and slide into the oven for a few minutes before serving. Our prediction? This super side dish will steal the spotlight.


Caramelized Onion

Mashed Potatoes


Caramelized Onion

  1. With the rack in the middle position, preheat the oven to 400°F (200°C).
  2. In a large skillet over medium heat, soften the onions in the butter, stirring frequently, for about 20 minutes or until they begin to caramelize.
  3. Add the wine and tomato paste. Continue cooking, while stirring, until the wine has completely evaporated. Season with salt and pepper. Transfer to a 12-inch (30 cm) round baking dish.

Mashed Potatoes

  1. Meanwhile, in a large pot of salted boiling water, cook the potatoes until very tender. Drain. With a potato masher, purée with the butter until smooth. Stir in the cream. Season with salt and pepper. Spread over the onions. Top with the cheese.
  2. Bake for 20 minutes. Finish under the broiler for 3 to 5 minutes or until the cheese is lightly golden brown. Let rest for 10 minutes. When ready to serve, sprinkle with the chives.


This dish can be made the day before. In this case, bake the gratin for about 40 minutes so that it’s piping hot.

To help you with this recipe

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Healthy Pick

Recipes with the \"Healthy Pick\" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.