Tarte à l’Oignon

  • Author: Mandy Pagano
  • Prep Time: 40 minutes
  • Cook Time: 40 minutes
  • Total Time: 1 hour 20 minutes
  • Yield: 8 slices
  • Category: Casserole, Eggs
  • Method: Baked
  • Cuisine: French


A Southern twist on this French country classic.


  • Small amount of butter or bacon drippings, to rub pie plate
  • 1-2 tbsp (1/2-1 fl oz/14-30 ml) avocado oil, as needed
  • 2 large yellow onions (approx. 10-11 oz/300 g) halved then very thinly sliced
  • 1 tbsp (1/2 oz/14 g) butter, salted
  • 1 tbsp (1/2 fl oz/14 ml) sherry vinegar
  • 1 lb (16 oz/454 g) smoked country sausage, sliced into small, bite-sized pieces
  • 1-2 tbsp (1/2-1 fl oz/14-30 ml) water, as needed
  • 4 large eggs
  • 1/2 c (4 fl oz/118 ml) heavy cream
  • 1/2 c (4 fl oz/118 ml) unsweetened carton coconut milk (the thin stuff in the box)
  • 1 tbsp coconut flour
  • 1/2-3/4 tsp sea salt (to taste, use 1/2 tsp if you’re more sensitive to salty foods)
  • 1/2 tsp Herbes de Provence
  • 1/4 tsp ground black pepper
  • 1/8 tsp ground nutmeg
  • 4 oz (113 g) Garlic & Herb Boursin Cheese


  1. Preheat the oven to 400°F and rub a heavy-bottomed deep dish pie plate (I use a heavy ceramic pie dish) well with bacon grease or butter. If desired (and for ease of transport), place the pie plate on a baking sheet.
  2. In a medium-large skillet, heat a tbsp avocado oil over medium-high heat until it’s hot and shimmery.
  3. Add the onions to the skillet and cook, stirring fairly constantly, until the onions begin getting golden. Immediately turn the heat down to medium-low, and keep the onions moving in the skillet by stirring until it cools off to a low and steady heat.
  4. Continue to cook the onions down over medium-low for about 15-20 minutes, stirring regularly to keep them from catching.
  5. When they start deepening into a darker golden brown color, add the butter and sherry vinegar and stir well. Continue to cook down until they are caramelized to your liking, from 5-15 minutes. I prefer a very deep caramel, which usually takes another 10-15 minutes.
  6. Remove the onions from the skillet and arrange evenly in the bottom of the pie plate.
  7. In the same skillet, add a touch extra avocado oil if needed and turn the heat up to medium.
  8. Add the sliced sausage and stir over medium heat until lightly browned and cooked through, about 7-10 minutes depending on how thickly you sliced it. A few minutes in, add a little water to the skillet to help scrape up any cooked on bits so all that flavor thoroughly coats the sausage.
  9. With a slotted spoon, remove the cooked sausage and put it evenly into the pie plate and let it all stand to cool a little. Leave behind any excess grease in the skillet. Trust me, adding the fat from the skillet is going to make your pie soupy and greasy, and there is plenty of fat without the extra.
  10. In a mixing bowl, whisk together the eggs, heavy cream, coconut milk, coconut flour, and seasonings until very well combined and smooth.
  11. Pour egg mixture evenly over the pie filling, then gently shake the pie dish.
  12. Break the Boursin cheese up into small chunks and gently distribute evenly over the top of the pie, then gently shake the pie plate again so it settles into it naturally.
  13. Bake in the center of the oven at 400°F for 30-40 minutes, or until it is set, the top is getting golden, and a toothpick inserted into the center comes out clean.
  14. Remove from the oven and let stand to cool for 15-20 minutes before slicing and serving hot.
  15. Enjoy!


Per slice (1/8 pie): 350 cal, 12.9 g protein, 29.5 g fat, 6.1 g carbs, 0.9 g fiber, 5.2 g NET carbs


  • Serving Size: 1/8 pie

Keywords: Tarte a l’Oignon, onion pie, french, Alsace, caramelize onion, sausage, quiche, crust less, quiche